For example, `1` is parsed as an integer literal, but it can be turned
into a float with the suffix `f32`. Now the error calls them "numeric
literals" and notes that you can add a float suffix since they can be
either integers or floats.
Handling the integer parsing properly instead of just unwrapping.
Note that the test is not catching the ICE because plain UI tests
[currently hide ICEs][compiletest_issue]. Once that issue is fixed, this
test would fail properly again.
[compiletest_issue]: https://github.com/laumann/compiletest-rs/issues/169
