fix null pointer exception in SourceViewerDecorationSupport

fInlineAnnotationColorKey might be not set

bundles/org.eclipse.ui.workbench.texteditor/src/org/eclipse/ui/texteditor/SourceViewerDecorationSupport.java

@@ -890,7 +890,7 @@ protected AnnotationPainter createAnnotationPainter() {
 		painter.addTextStyleStrategy(AnnotationPreference.STYLE_UNDERLINE, fgUnderlineStrategy);
 
 		ColorRegistry registry = JFaceResources.getColorRegistry();
-		if (registry != null) {
+		if (registry != null && fInlineAnnotationColorKey != null) {
 			Color color = registry.get(fInlineAnnotationColorKey);
 			painter.setInlineAnnotationColor(color);
 			if (fPropertyChangeListener != null) {