[code-reflection] RFR: throw instead returning when erasing checked to unchecked exception

[Hannes Greule]

As discussed in https://mail.openjdk.org/pipermail/babylon-dev/2024-January/000006.html, I change the `erase` method to `eraseAndThrow` and added a test as suggested. I ensured that the test fails without my change and does not fail with it.

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Commit messages:
 - throw instead returning when erasing checked to unchecked exception

Changes: https://git.openjdk.org/babylon/pull/2/files
 Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=2&range=00
  Stats: 81 lines in 2 files changed: 77 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/babylon/pull/2.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/2/head:pull/2

PR: https://git.openjdk.org/babylon/pull/2