fix bug when SD tried to display the source file that not exists (e.g. the symbols are present but the sources aren't - see Prism).

src/Main/Base/Project/Src/Services/Debugger/CurrentLineBookmark.cs

@@ -29,6 +29,8 @@ namespace ICSharpCode.SharpDevelop.Debugging
 				SetPosition(tecp.TextEditor.FileName, tecp.TextEditor.Document, markerStartLine, markerStartColumn, markerEndLine, markerEndColumn);
 			} else {
 				lock (syncObject) {
+					// get the decompiled view if exists
+					if (viewContent != null && viewContent.Control != null) {
 						dynamic codeView = viewContent.Control;
 						var document = codeView.TextEditor.Document as IDocument;
 						SetPosition(codeView.Adapter.FileName, document, markerStartLine, markerStartColumn, markerEndLine, markerEndColumn);
@@ -39,6 +41,7 @@ namespace ICSharpCode.SharpDevelop.Debugging
 					}
 				}
 			}
+		}
 		
 		public static void SetPosition(FileName fileName, IDocument document, int markerStartLine, int markerStartColumn, int markerEndLine, int markerEndColumn)
 		{