cloudflare: Two uncovered spots

* `src/executionContext.ts`: 0% statements, 0% branches.
* `src/withSentry.ts`: 33% branch coverage (see C2).

**Work item.** Add unit tests for both. `executionContext.ts` should be cheap.

**Prior art ***(related history only)*. Three open issues cover Cloudflare test infrastructure but not these two files: [#22523]() "Add tests with @cloudflare/vitest-pool-workers", [#23610]() "Create E2E tests that use real Cloudflare Workers", and [#20874]() "Create canary tests for Cloudflare E2E and integration tests".

Start by reading src/executionContext.ts and src/withSentry.ts, then review the coverage report, especially the C2 branch in withSentry.ts. Add unit tests for the uncovered statements and branches in both files, with executionContext.ts treated as the smaller task. Done means both files have tests covering the identified gaps.

由索引模型根据 Issue 内容生成。