Fix App Check swallowing errors and returning cached token

[nermeen-mattar]

Summary
The current implementation checks for result.error, but this property does not exist. Instead, errors are stored in result.internalError. This fix ensures that the correct property is checked, preventing silent failures and ensuring proper error handling.
This change ensures that when an error occurs, it is properly surfaced instead of returning a cached token incorrectly.

[changeset-bot]

🦋 Changeset detected

Latest commit: 788d332

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
@firebase/app-check	Minor
@firebase/app-check-compat	Patch
firebase	Patch

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[nermeen-mattar]

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