Better error when force-compile fails

pkg/dev_compiler/lib/src/compiler/compiler.dart

 // Copyright (c) 2016, 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.
 
 import 'dart:collection' show HashSet, Queue;
 import 'dart:convert' show JSON;
 import 'dart:io' show File;
 
 import 'package:analyzer/analyzer.dart'
     show AnalysisError, CompilationUnit, ErrorSeverity;
@@ skipping 197 matching lines @@
     var messages = <String>[];
     for (var e in errors) {
       var m = formatError(context, e);
       if (m != null) messages.add(m);
     }
 
     if (!options.unsafeForceCompile &&
         errors.any((e) => _isFatalError(e, options))) {
       return new JSModuleFile.invalid(unit.name, messages, options);
     }
-    var codeGenerator =
-        new CodeGenerator(context, summaryData, options, _extensionTypes);
-    return codeGenerator.compile(unit, trees, messages);
+
+    try {
+      var codeGenerator =
+          new CodeGenerator(context, summaryData, options, _extensionTypes);
+      return codeGenerator.compile(unit, trees, messages);
+    } catch (e) {
+      if (errors.any((e) => _isFatalError(e, options))) {
+        // Force compilation failed.  Suppress the exception and report
+        // the static errors instead.
+        assert(options.unsafeForceCompile);
+        return new JSModuleFile.invalid(unit.name, messages, options);
+      }
+      rethrow;
+    }
   }
 }
 
 class CompilerOptions {
   /// Whether to emit the source mapping file.
   ///
   /// This supports debugging the original source code instead of the generated
   /// code.
   final bool sourceMap;
 
@@ skipping 394 matching lines @@
     case "dart":
     case "package":
     case "file":
       // A valid URI.
       return uri;
     default:
       // Assume a file path.
       return new Uri.file(path.absolute(source));
   }
 }