Improve error reporting on status page

pkg/analysis_server/lib/src/get_handler.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library analysis_server.src.get_handler;
 
 import 'dart:collection';
 import 'dart:convert';
 import 'dart:io';
 import 'dart:math';
@@ skipping 271 matching lines @@
         SourceEntry entry = context.getReadableSourceEntryOrNull(source);
         if (entry == null) {
           buffer.write('<p>Not found.</p>');
           return;
         }
         CompilationUnit ast = (entry as DartEntry).anyParsedCompilationUnit;
         if (ast == null) {
           buffer.write('<p>null</p>');
           return;
         }
-        ast.accept(new AstWriter(buffer));
+        AstWriter writer = new AstWriter(buffer);
+        ast.accept(writer);
+        if (writer.exceptions.isNotEmpty) {
+          buffer.write('<h3>Exceptions while creating page</h3>');
+          for (CaughtException exception in writer.exceptions) {
+            _writeException(buffer, exception);
+          }
+        }
       });
     });
   }
 
   /**
    * Return a response containing information about a single source file in the
    * cache.
    */
   void _returnCacheEntry(HttpRequest request) {
     AnalysisServer analysisServer = _server.analysisServer;
@@ skipping 1170 matching lines @@
     } else if (value is Element) {
       String link =
           _makeLink(ELEMENT_PATH, linkParameters, value.runtimeType.toString());
       buffer.write('<i>$link</i>');
     } else {
       buffer.write(HTML_ESCAPE.convert(value.toString()));
       buffer.write(' <i>(${value.runtimeType.toString()})</i>');
     }
   }
 }