[INFO] cloning repository https://github.com/maxastyler/Spirograph [INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/maxastyler/Spirograph" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmaxastyler%2FSpirograph", kill_on_drop: false }` [INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmaxastyler%2FSpirograph'... [INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }` [INFO] [stdout] d639d179214179e4843bca5cbd646dc9a1959e5d [INFO] checking maxastyler/Spirograph against master#00bfd6b2734d9c28a147bf237490995731781fdd for pr-117984 [INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmaxastyler%2FSpirograph" "/workspace/builds/worker-0-tc1/source", kill_on_drop: false }` [INFO] [stderr] Cloning into '/workspace/builds/worker-0-tc1/source'... [INFO] [stderr] done. [INFO] validating manifest of git repo https://github.com/maxastyler/Spirograph on toolchain 00bfd6b2734d9c28a147bf237490995731781fdd [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+00bfd6b2734d9c28a147bf237490995731781fdd" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }` [INFO] started tweaking git repo https://github.com/maxastyler/Spirograph [INFO] finished tweaking git repo https://github.com/maxastyler/Spirograph [INFO] tweaked toml for git repo https://github.com/maxastyler/Spirograph written to /workspace/builds/worker-0-tc1/source/Cargo.toml [INFO] crate git repo https://github.com/maxastyler/Spirograph already has a lockfile, it will not be regenerated [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+00bfd6b2734d9c28a147bf237490995731781fdd" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }` [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc1/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+00bfd6b2734d9c28a147bf237490995731781fdd" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }` [INFO] [stdout] 83b8fdf31e6a624dfd382ae0c5081201881b1368faa91fb6214ef559eeae835d [INFO] running `Command { std: "docker" "start" "-a" "83b8fdf31e6a624dfd382ae0c5081201881b1368faa91fb6214ef559eeae835d", kill_on_drop: false }` [INFO] running `Command { std: "docker" "inspect" "83b8fdf31e6a624dfd382ae0c5081201881b1368faa91fb6214ef559eeae835d", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "83b8fdf31e6a624dfd382ae0c5081201881b1368faa91fb6214ef559eeae835d", kill_on_drop: false }` [INFO] [stdout] 83b8fdf31e6a624dfd382ae0c5081201881b1368faa91fb6214ef559eeae835d [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc1/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=forbid" "-e" "RUSTDOCFLAGS=--cap-lints=forbid" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+00bfd6b2734d9c28a147bf237490995731781fdd" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }` [INFO] [stdout] d05bbabc3627c95ce8e044cb677b235c3d59e8f8e78fce5a802f1c193580c390 [INFO] running `Command { std: "docker" "start" "-a" "d05bbabc3627c95ce8e044cb677b235c3d59e8f8e78fce5a802f1c193580c390", kill_on_drop: false }` [INFO] [stderr] error: failed to create directory `/opt/rustwide/target/debug/.fingerprint/either-5c8ee8e972c85a11` [INFO] [stderr] [INFO] [stderr] Caused by: [INFO] [stderr] No space left on device (os error 28) [INFO] running `Command { std: "docker" "inspect" "d05bbabc3627c95ce8e044cb677b235c3d59e8f8e78fce5a802f1c193580c390", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "d05bbabc3627c95ce8e044cb677b235c3d59e8f8e78fce5a802f1c193580c390", kill_on_drop: false }` [INFO] [stdout] d05bbabc3627c95ce8e044cb677b235c3d59e8f8e78fce5a802f1c193580c390 [INFO] checking maxastyler/Spirograph against try#aa7c6ba69acce8b10a275eabfe6157ea72c8b599 for pr-117984 [INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmaxastyler%2FSpirograph" "/workspace/builds/worker-0-tc2/source", kill_on_drop: false }` [INFO] [stderr] Cloning into '/workspace/builds/worker-0-tc2/source'... [INFO] [stderr] done. [INFO] validating manifest of git repo https://github.com/maxastyler/Spirograph on toolchain aa7c6ba69acce8b10a275eabfe6157ea72c8b599 [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+aa7c6ba69acce8b10a275eabfe6157ea72c8b599" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }` [INFO] started tweaking git repo https://github.com/maxastyler/Spirograph [INFO] finished tweaking git repo https://github.com/maxastyler/Spirograph [INFO] tweaked toml for git repo https://github.com/maxastyler/Spirograph written to /workspace/builds/worker-0-tc2/source/Cargo.toml [INFO] crate git repo https://github.com/maxastyler/Spirograph already has a lockfile, it will not be regenerated [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+aa7c6ba69acce8b10a275eabfe6157ea72c8b599" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }` [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc2/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+aa7c6ba69acce8b10a275eabfe6157ea72c8b599" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }` [INFO] [stdout] a1ef034a262f9d1324734b2f23eb9a9d0729810ed974ed650ab40fb602f7d24e [INFO] running `Command { std: "docker" "start" "-a" "a1ef034a262f9d1324734b2f23eb9a9d0729810ed974ed650ab40fb602f7d24e", kill_on_drop: false }` [INFO] running `Command { std: "docker" "inspect" "a1ef034a262f9d1324734b2f23eb9a9d0729810ed974ed650ab40fb602f7d24e", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "a1ef034a262f9d1324734b2f23eb9a9d0729810ed974ed650ab40fb602f7d24e", kill_on_drop: false }` [INFO] [stdout] a1ef034a262f9d1324734b2f23eb9a9d0729810ed974ed650ab40fb602f7d24e [INFO] checking maxastyler/Spirograph against try#aa7c6ba69acce8b10a275eabfe6157ea72c8b599 for pr-117984 [INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmaxastyler%2FSpirograph" "/workspace/builds/worker-0-tc2/source", kill_on_drop: false }` [INFO] [stderr] Cloning into '/workspace/builds/worker-0-tc2/source'... [INFO] [stderr] done. [INFO] validating manifest of git repo https://github.com/maxastyler/Spirograph on toolchain aa7c6ba69acce8b10a275eabfe6157ea72c8b599 [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+aa7c6ba69acce8b10a275eabfe6157ea72c8b599" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }` [INFO] started tweaking git repo https://github.com/maxastyler/Spirograph [INFO] finished tweaking git repo https://github.com/maxastyler/Spirograph [INFO] tweaked toml for git repo https://github.com/maxastyler/Spirograph written to /workspace/builds/worker-0-tc2/source/Cargo.toml [INFO] crate git repo https://github.com/maxastyler/Spirograph already has a lockfile, it will not be regenerated [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+aa7c6ba69acce8b10a275eabfe6157ea72c8b599" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }` [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc2/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+aa7c6ba69acce8b10a275eabfe6157ea72c8b599" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }` [INFO] [stdout] a36015fee7811c78d560ffbfe169ffd3053c5e9de3198f821c866a75b6c90b94 [INFO] running `Command { std: "docker" "start" "-a" "a36015fee7811c78d560ffbfe169ffd3053c5e9de3198f821c866a75b6c90b94", kill_on_drop: false }` [INFO] running `Command { std: "docker" "inspect" "a36015fee7811c78d560ffbfe169ffd3053c5e9de3198f821c866a75b6c90b94", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "a36015fee7811c78d560ffbfe169ffd3053c5e9de3198f821c866a75b6c90b94", kill_on_drop: false }` [INFO] [stdout] a36015fee7811c78d560ffbfe169ffd3053c5e9de3198f821c866a75b6c90b94 [INFO] checking maxastyler/Spirograph against try#aa7c6ba69acce8b10a275eabfe6157ea72c8b599 for pr-117984 [INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmaxastyler%2FSpirograph" "/workspace/builds/worker-0-tc2/source", kill_on_drop: false }` [INFO] [stderr] Cloning into '/workspace/builds/worker-0-tc2/source'... [INFO] [stderr] done. [INFO] validating manifest of git repo https://github.com/maxastyler/Spirograph on toolchain aa7c6ba69acce8b10a275eabfe6157ea72c8b599 [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+aa7c6ba69acce8b10a275eabfe6157ea72c8b599" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }` [INFO] started tweaking git repo https://github.com/maxastyler/Spirograph [INFO] finished tweaking git repo https://github.com/maxastyler/Spirograph [INFO] tweaked toml for git repo https://github.com/maxastyler/Spirograph written to /workspace/builds/worker-0-tc2/source/Cargo.toml [INFO] crate git repo https://github.com/maxastyler/Spirograph already has a lockfile, it will not be regenerated [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+aa7c6ba69acce8b10a275eabfe6157ea72c8b599" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }` [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc2/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+aa7c6ba69acce8b10a275eabfe6157ea72c8b599" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }` [INFO] [stderr] Error response from daemon: write /var/lib/docker/containers/6b0deef56ec7e1a6ae1590d4106b559fa23c0dcbdb687ec37fe155e29eaae4a6/.tmp-hostconfig.json3068863699: no space left on device [INFO] checking maxastyler/Spirograph against try#aa7c6ba69acce8b10a275eabfe6157ea72c8b599 for pr-117984 [INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmaxastyler%2FSpirograph" "/workspace/builds/worker-0-tc2/source", kill_on_drop: false }` [INFO] [stderr] Cloning into '/workspace/builds/worker-0-tc2/source'... [INFO] [stderr] done. [INFO] validating manifest of git repo https://github.com/maxastyler/Spirograph on toolchain aa7c6ba69acce8b10a275eabfe6157ea72c8b599 [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+aa7c6ba69acce8b10a275eabfe6157ea72c8b599" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }` [INFO] started tweaking git repo https://github.com/maxastyler/Spirograph [INFO] finished tweaking git repo https://github.com/maxastyler/Spirograph [INFO] tweaked toml for git repo https://github.com/maxastyler/Spirograph written to /workspace/builds/worker-0-tc2/source/Cargo.toml [INFO] crate git repo https://github.com/maxastyler/Spirograph already has a lockfile, it will not be regenerated [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+aa7c6ba69acce8b10a275eabfe6157ea72c8b599" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }` [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc2/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+aa7c6ba69acce8b10a275eabfe6157ea72c8b599" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }` [INFO] [stderr] Error response from daemon: mkdir /var/lib/docker/overlay2/ebddd7331dc1b64cfa673ec5906a71b7fbde250a7b9882e29dd365726db113f3/merged/opt/rustwide: no space left on device [INFO] checking maxastyler/Spirograph against try#aa7c6ba69acce8b10a275eabfe6157ea72c8b599 for pr-117984 [INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmaxastyler%2FSpirograph" "/workspace/builds/worker-0-tc2/source", kill_on_drop: false }` [INFO] [stderr] Cloning into '/workspace/builds/worker-0-tc2/source'... [INFO] [stderr] done. [INFO] validating manifest of git repo https://github.com/maxastyler/Spirograph on toolchain aa7c6ba69acce8b10a275eabfe6157ea72c8b599 [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+aa7c6ba69acce8b10a275eabfe6157ea72c8b599" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }` [INFO] started tweaking git repo https://github.com/maxastyler/Spirograph [INFO] finished tweaking git repo https://github.com/maxastyler/Spirograph [INFO] tweaked toml for git repo https://github.com/maxastyler/Spirograph written to /workspace/builds/worker-0-tc2/source/Cargo.toml [INFO] crate git repo https://github.com/maxastyler/Spirograph already has a lockfile, it will not be regenerated [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+aa7c6ba69acce8b10a275eabfe6157ea72c8b599" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }` [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc2/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+aa7c6ba69acce8b10a275eabfe6157ea72c8b599" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }` [INFO] [stderr] Error response from daemon: chown /var/lib/docker/overlay2/b1ccd5f012b52548ad8d06fb3893260f84df2f1e74948ee260212a13b616a07b/work/work: no such file or directory [ERROR] this task or one of its parent failed! [ERROR] command failed: exit status: 1 [ERROR] note: run with `RUST_BACKTRACE=1` to display a backtrace.