_AuthTokenProvider.onTokenChanged' ('Stream<String?> Function()') isn't a valid override of 'AuthTokenProvider.onTokenChanged

[sgehrman]

Code has errors

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"severity": 8,
"message": "'_AuthTokenProvider.onTokenChanged' ('Stream<String?> Function()') isn't a valid override of 'AuthTokenProvider.onTokenChanged' ('Stream<Future?> Function()').",
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