Fixes case where the annotator would attempt to access an editor that is already disposed (#75)

Author: jimkyndemeyer

src/main/com/intellij/lang/jsgraphql/ide/annotator/JSGraphQLAnnotator.java

@@ -86,6 +86,9 @@ public void apply(@NotNull PsiFile file, JSGraphQLAnnotationResult annotationRes
         if(annotationResult != null) {
             try {
                 final Editor editor = annotationResult.getEditor();
+                if(editor.isDisposed()) {
+                    return;
+                }
                 final String fileName = file.getVirtualFile().getPath();
                 final List<JSGraphQLErrorResult> errors = Lists.newArrayList();
                 final JSGraphQLLanguageWarningAnnotator internalAnnotator = new JSGraphQLLanguageWarningAnnotator();