bug: deno coverage unexpectedly failing on simple snippet

[iuioiua]

See https://github.com/denoland/std/actions/runs/10941340431/job/30375761825?pr=6018

Task cov:gen deno task cov --lcov --output=cov.lcov
Task cov deno coverage --ignore="**/*.generated.mjs,**/_test_utils.ts,.github" "--lcov" "--output=cov.lcov"
error: Failed to fetch "file:///home/runner/work/std/std/assert/equal.ts$23-29.ts" from cache.
          Before generating coverage report, run `deno test --coverage` to ensure consistent state.
Error: Process completed with exit code 1.

Failing on this simple snippet:
https://github.com/denoland/std/blob/6a4eb6cb9185b0b9e0816a227c04b5bf039b99ef/assert/equals.ts#L19-L24

To reproduce:

1. Clone std
2. Checkout fix: update codebase to work with Deno RC std#6018
3. Run deno task test
4. Run deno task cov:gen

CC @magurotuna