Panic when running `build-bom generate-bitcode` (with no arguments)

[langston-barrett]

Revision:

$ git rev-parse --short HEAD                       
8056803

Reproduce:

$ ./target/debug/build-bom  generate-bitcode
thread 'main' panicked at 'assertion failed: mid <= self.len()', /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/slice/mod.rs:1537:9
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Backtraces

``` root@37b1efb3efde:/x# /build-bom/target/x86_64-unknown-linux-musl/release/build-bom generate-bitcode thread 'main' panicked at 'assertion failed: mid <= self.len()', /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/slice/mod.rs:1537:9 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace root@37b1efb3efde:/x# RUST_BACKTRACE=1 /build-bom/target/x86_64-unknown-linux-musl/release/build-bom generate-bitcode thread 'main' panicked at 'assertion failed: mid <= self.len()', /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/slice/mod.rs:1537:9 stack backtrace: 0: rust_begin_unwind at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/panicking.rs:517:5 1: core::panicking::panic_fmt at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/panicking.rs:100:14 2: core::panicking::panic at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/panicking.rs:50:5 3: bom::bom::bitcode::bitcode_entrypoint 4: bom::run_bom 5: build_bom::main note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace. root@37b1efb3efde:/x# RUST_BACKTRACE=full /build-bom/target/x86_64-unknown-linux-musl/release/build-bom generate-bitcode thread 'main' panicked at 'assertion failed: mid <= self.len()', /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/slice/mod.rs:1537:9 stack backtrace: 0: 0x7f731c605e3c - std::backtrace_rs::backtrace::libunwind::trace::hc1bc96ddb4426aa4 at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/../../backtrace/src/backtrace/libunwind.rs:90:5 1: 0x7f731c605e3c - std::backtrace_rs::backtrace::trace_unsynchronized::h923980a653d66493 at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5 2: 0x7f731c605e3c - std::sys_common::backtrace::_print_fmt::h9c757c85a437b931 at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/sys_common/backtrace.rs:67:5 3: 0x7f731c605e3c - ::fmt::hd4daee6a3bf7c86e at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/sys_common/backtrace.rs:46:22 4: 0x7f731c6401cc - core::fmt::write::hb92fcd00ba9c1ad2 at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/fmt/mod.rs:1163:17 5: 0x7f731c601775 - std::io::Write::write_fmt::he1040163a0175759 at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/io/mod.rs:1696:15 6: 0x7f731c607de0 - std::sys_common::backtrace::_print::h41aed1f85e85fe81 at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/sys_common/backtrace.rs:49:5 7: 0x7f731c607de0 - std::sys_common::backtrace::print::h80502ae1de52b70b at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/sys_common/backtrace.rs:36:9 8: 0x7f731c607de0 - std::panicking::default_hook::{{closure}}::ha8bcafa5b9176f3f at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/panicking.rs:210:50 9: 0x7f731c607995 - std::panicking::default_hook::hfaee58ed0a065bec at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/panicking.rs:227:9 10: 0x7f731c608494 - std::panicking::rust_panic_with_hook::h8ce3328d937db5aa at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/panicking.rs:624:17 11: 0x7f731c607f42 - std::panicking::begin_panic_handler::{{closure}}::h1f2295b855ba5030 at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/panicking.rs:519:13 12: 0x7f731c6062e4 - std::sys_common::backtrace::__rust_end_short_backtrace::h17092a58b60b0566 at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/sys_common/backtrace.rs:139:18 13: 0x7f731c607ed9 - rust_begin_unwind at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/panicking.rs:517:5 14: 0x7f731c499431 - core::panicking::panic_fmt::hcf6bd03e382adeab at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/panicking.rs:100:14 15: 0x7f731c49937d - core::panicking::panic::he7efc04572bf92e9 at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/panicking.rs:50:5 16: 0x7f731c4fef2f - bom::bom::bitcode::bitcode_entrypoint::h5935250f50302372 17: 0x7f731c49f905 - bom::run_bom::h10a6bcd1fede10ab 18: 0x7f731c499eb8 - build_bom::main::hb1f847b24e043138 19: 0x7f731c49a253 - std::sys_common::backtrace::__rust_begin_short_backtrace::hddd118dbbd843840 20: 0x7f731c49a10d - std::rt::lang_start::{{closure}}::h8b6ab5d1237deb63 21: 0x7f731c605b11 - core::ops::function::impls:: for &F>::call_once::h37d528e2b7386a19 at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/ops/function.rs:259:13 22: 0x7f731c605b11 - std::panicking::try::do_call::h21f3d980e271aebe at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/panicking.rs:403:40 23: 0x7f731c605b11 - std::panicking::try::h6366c75894a5ee3f at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/panicking.rs:367:19 24: 0x7f731c605b11 - std::panic::catch_unwind::hbab33c6a69c714f4 at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/panic.rs:133:14 25: 0x7f731c605b11 - std::rt::lang_start_internal::{{closure}}::h4a2c188522fb7f4a at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/rt.rs:128:48 26: 0x7f731c605b11 - std::panicking::try::do_call::h9b4b672a4b3537ad at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/panicking.rs:403:40 27: 0x7f731c605b11 - std::panicking::try::h9c95acfa69428cd5 at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/panicking.rs:367:19 28: 0x7f731c605b11 - std::panic::catch_unwind::h137c802160173f20 at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/panic.rs:133:14 29: 0x7f731c605b11 - std::rt::lang_start_internal::h89221b25a17002da at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/rt.rs:128:20 30: 0x7f731c499f12 - main ```