Roc panic in bumpalo-3.14.0 when rendering expect failure

[imclerran]

Haven't been able to minimize this error away from using Str.from_utf8, however the following code will produce the panic:

module []

expect
    utf8 = [0b1101_1111, 0b0011_1111]
    err = Err(BadUtf8({ index: 1, problem: ExpectedContinuation }))
    str_res = utf8 |> Str.from_utf8
    str_res == err

If index is changed to 0, the expect will pass, and since the failure is not rendered, the panic is not encountered. The same error can be reproduced by setting index to 0, but changing the tag assigned to problem.

The stack trace is as follows:

thread 'main' panicked at /Users/imclerran/.cargo/registry/src/index.crates.io-6f17d22bba15001f/bumpalo-3.14.0/src/lib.rs:1854:5:
out of memory
stack backtrace:
   0: rust_begin_unwind
             at /rustc/25ef9e3d85d934b27d9dada2f9dd52b1dc63bb04/library/std/src/panicking.rs:647:5
   1: core::panicking::panic_fmt
             at /rustc/25ef9e3d85d934b27d9dada2f9dd52b1dc63bb04/library/core/src/panicking.rs:72:14
   2: bumpalo::oom
   3: roc_repl_eval::eval::addr_to_ast
   4: roc_repl_eval::eval::expr_of_tag
   5: roc_repl_eval::eval::addr_to_ast
   6: roc_repl_expect::get_values
   7: roc_repl_expect::run::render_expect_failure
   8: roc_cli::test
   9: roc::main
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.