`@MainActor` annotation on `@Test` method crashes the test plugin

[filip-sakel]

Here's a reproducer. I'm using the 6.2.3 Release Wasm SDK (non-embedded) with Swift 6.2.3 Release on aarch64-unknown-linux-gnu with swift tools version 6.0 (as shown in the linked repo). I'm getting the following error:

◇ Test run started.
↳ Testing Library Version: 6.2.3 (48a471ab313e858)
↳ Target Platform: wasm32-unknown-wasip
◇ Test myTest() started.
=================================================================================================
Detected that the test execution ended without a termination signal from the testing framework.
Hint: This typically means that a continuation leak occurred.
=================================================================================================
error: Error: Test failed with status 1

Observations

1. I get the same error whether the @MainActor-isolated function synchronous is asynchronous.
2. Removing the @MainActor attribute from the function signature and wrapping the function body in await MainActor.run { ... } produces the same error.