fix : Guard against all uncaught exception in the serial executor block

[pmathew92]

Changes

• Adds a runCatchingOnExecutor inline helper in BaseCredentialsManager that wraps the serialExecutor lambda body with a try/catch(Throwable), routing any unhandled exception to
  callback.onFailure(UNKNOWN_ERROR)
• Wraps all 6 executor-based methods (getSsoCredentials, getCredentials/continueGetCredentials, getApiCredentials/continueGetApiCredentials) in both CredentialsManager and SecureCredentialsManager
• Removes redundant catch(RuntimeException) blocks from all methods since the outer catch now handles them
• Adds catch(CredentialsManagerException) for STORE_FAILED in SecureCredentialsManager.continueGetApiCredentials (was missing vs other methods)

Problem

Closes #968

Test plan

• Added 5 unit tests in CredentialsManagerTest verifying the outer catch handles exceptions from storage reads and network calls
• Added 4 unit tests in SecureCredentialsManagerTest for the same scenarios
• All 216 existing + new tests pass (93 CredentialsManager, 123 SecureCredentialsManager)
• Manual test: Install sample app → enable airplane mode → tap "Timeout Race" → verify snackbar (not crash)

Testing

Please describe how this can be tested by reviewers. Be specific about anything not tested and reasons why. Since this library has unit testing, tests should be added for new functionality and existing tests should complete without errors.

• This change adds unit test coverage

• This change adds integration test coverage

• This change has been tested on the latest version of the platform/language or why not

Checklist

• I have read the Auth0 general contribution guidelines

• I have read the Auth0 Code of Conduct

• All existing and new tests complete without errors

[utkrishtsahu]

atching Throwable here means we'd also swallow OutOfMemoryError, StackOverflowError, etc. — situations where the JVM is in a bad state and the app really should crash. The old code only caught RuntimeException. Could we narrow this to Exception instead? Or re-throw Error subtypes so fatal problems don't get silently eaten:

} catch (e: Exception) {
callback.onFailure(
CredentialsManagerException(CredentialsManagerException.Code.UNKNOWN_ERROR, e)
)

[pmathew92]

Good point on catching too broadly. However, I'm intentionally keeping Throwable here — this is an SDK running on a background executor, and the entire purpose of this fix (#968) is to prevent unhandled exceptions from silently killing the host app. The rationale is that a library should never be the reason an app force-closes without explanation — the host app should own its crash policy.

[utkrishtsahu]

can we add log
line here? Something like:

} catch (t: Throwable) {
Log.e("BaseCredentialsManager", "Unexpected error in executor block", t)
callback.onFailure(...)
}
will be helpful if a customer reports a weird failure

[pmathew92]

Good point. Added log to record the error