sbt-test: scripted test succeeds while they should fail

[hamzaremmal]

Compiler version

a3dde8b

Minimized code

Add an assert(false) at the end of this file: https://github.com/scala/scala3/blob/a3dde8bd9e57a7c6caf089d4d793d5aed9103abd/sbt-test/scala2-compat/erasure/dottyApp/Main.scala

Output

The test will succeed

Expectation

The test should fail

Notes

This issue was discovered while working on #22517 (See #22517 (comment)).
While testing locally, it appears that any error of type LinkageError is not considered a failure.
Checking on the sbt repository later, I found an issue raised a few years ago: sbt/sbt#6852