[366240] [misc] Semantic Highlighter throws exceptions for unknown contenttypes

bundles/org.eclipse.wst.sse.ui/src/org/eclipse/wst/sse/ui/internal/style/SemanticHighlightingReconciler.java

diff --git a/bundles/org.eclipse.wst.sse.ui/src/org/eclipse/wst/sse/ui/internal/style/SemanticHighlightingReconciler.java b/bundles/org.eclipse.wst.sse.ui/src/org/eclipse/wst/sse/ui/internal/style/SemanticHighlightingReconciler.java
index 8318c97..00a99f4 100644
--- a/bundles/org.eclipse.wst.sse.ui/src/org/eclipse/wst/sse/ui/internal/style/SemanticHighlightingReconciler.java
+++ b/bundles/org.eclipse.wst.sse.ui/src/org/eclipse/wst/sse/ui/internal/style/SemanticHighlightingReconciler.java
@@ -239,8 +239,7 @@
 	}
 
 	public void setDocument(IDocument document) {
-		fDocument = document;
-//		refresh();
+		fDocument = (document instanceof IStructuredDocument) ? document : null;
 	}
 
 	public void initialReconcile() {