IFile parameter can not be null

org.eclipse.wst.sse.core.internal.util.Assert$AssertionFailedException: IFile parameter can not be null
	at org.eclipse.wst.sse.core.internal.util.Assert.isNotNull(Assert.java:124)
	at org.eclipse.wst.sse.core.internal.model.ModelManagerImpl.getExistingModelForRead(ModelManagerImpl.java:1272)
	at org.eclipse.angularjs.internal.ui.validation.AbstractValidator.validate(AbstractValidator.java:126)
	at org.eclipse.angularjs.internal.ui.validation.AbstractValidator.validate(AbstractValidator.java:118)
	at org.eclipse.wst.sse.ui.internal.reconcile.validator.ReconcileStepForValidator.validate(ReconcileStepForValidator.java:381)
	at org.eclipse.wst.sse.ui.internal.reconcile.validator.ReconcileStepForValidator.reconcileModel(ReconcileStepForValidator.java:259)
	at org.eclipse.jface.text.reconciler.AbstractReconcileStep.reconcile(AbstractReconcileStep.java:95)
	at org.eclipse.wst.sse.ui.internal.reconcile.validator.ValidatorStrategy.reconcile(ValidatorStrategy.java:269)
	at org.eclipse.wst.sse.ui.internal.reconcile.DocumentRegionProcessor.process(DocumentRegionProcessor.java:321)
	at org.eclipse.wst.sse.ui.internal.reconcile.StructuredRegionProcessor.process(StructuredRegionProcessor.java:258)
	at org.eclipse.wst.sse.ui.internal.reconcile.DirtyRegionProcessor$BackgroundThread.run(DirtyRegionProcessor.java:691)