NPE from FileSystemState.getFilesForPath (file_state.dart:919)

[devoncarew]

Seen by 1 internal user 10 times:

NoSuchMethodError: The method 'toList' was called on null.
Receiver: null
Tried calling: toList()
	at Object.noSuchMethod	(dart:core)
	at FileSystemState.getFilesForPath	(file_state.dart:919)
	at FileTracker.verifyApiSignature.<fn>	(file_tracker.dart:182)
	at PerformanceLog.run	(performance_logger.dart:34)
	at FileTracker.verifyApiSignature	(file_tracker.dart:173)
	at AnalysisDriver.getFileSync	(driver.dart:596)
	at AnalysisSessionImpl.getFile	(session.dart:115)
	at newDiagnosticMessage	(protocol_server.dart:157)
	at newAnalysisError_fromEngine.<fn>	(protocol_server.dart:136)
	at ListIterable.toList	(dart:_internal)
	at newAnalysisError_fromEngine	(protocol_server.dart:137)
	at mapEngineErrors	(protocol_server.dart:93)
	at doAnalysisError_listFromEngine	(protocol_server.dart:36)
	at ServerContextManagerCallbacks.addAnalysisDriver.<fn>	(analysis_server.dart:679)