Categorize crashes.

dart/frog/leg/scanner/scanner_task.dart

 // Copyright (c) 2011, 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.
 
 class ScannerTask extends CompilerTask {
   ScannerTask(Compiler compiler) : super(compiler);
   String get name() => 'Scanner';
 
   void scan(CompilationUnitElement compilationUnit) {
     measure(() {
       Link<Element> elements = scanElements(compilationUnit);
       for (Link<Element> link = elements; !link.isEmpty(); link = link.tail) {
         Element existing = compiler.universe.find(link.head.name);
         if (existing !== null) {
           Node node = link.head.parseNode(compiler, compiler);
           // TODO(ahe): Is this the right place to handle this?
           compiler.cancel('Duplicate definition', node: node);
         }
         compiler.universe.define(link.head);
       }
     });
   }
 
   Link<Element> scanElements(CompilationUnitElement compilationUnit) {
     Script script = compilationUnit.script;
-    Token tokens = new StringScanner(script.text).tokenize();
+    Token tokens;
+    try {
+      tokens = new StringScanner(script.text).tokenize();
+    } catch (MalformedInputException ex) {
+      Token token;
+      var message;
+      if (ex.message is int) {
+        token = new Token(EOF_INFO, ex.message);
+        message = 'unexpected character';
+      } else {
+        token = new Token(EOF_INFO, 0);
+        message = ex.message;
+      }
+      compiler.cancel(message, token: token);
+      throw 'unrecoverable error';

[karlklose, 2012/01/17 16:54:36]

Compiler.cancel should terminate the compilation, so you do not need to throw.

+    }
     ElementListener listener = new ElementListener(compiler, compilationUnit);
     PartialParser parser = new PartialParser(listener);
     parser.parseUnit(tokens);
     return listener.topLevelElements;
   }
 }