Change the error handling in dart:io

runtime/bin/process_impl.dart

 // Copyright (c) 2012, 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 _ProcessStartStatus {
   int _errorCode;  // Set to OS error code if process start failed.
   String _errorMessage;  // Set to OS error message if process start failed.
 }
 
 
@@ skipping 148 matching lines @@
                           _arguments,
                           _workingDirectory,
                           _environment,
                           _in,
                           _out,
                           _err,
                           _exitHandler,
                           status);
     if (!success) {
       close();
-      if (_onError !== null) {
-        _onError(new ProcessException(status._errorMessage, status._errorCode));
-        return;
-      }
+      _reportError(new ProcessException(status._errorMessage, status._errorCode));
+      return;
     }
     _started = true;
 
     // Make sure to activate socket handlers now that the file
     // descriptors have been set.
     _in._activateHandlers();
     _out._activateHandlers();
     _err._activateHandlers();
 
     // Setup an exit handler to handle internal cleanup and possible
@@ skipping 52 matching lines @@
 
   OutputStream get stdin() {
     if (_closed) {
       throw new ProcessException("Process closed");
     }
     return _out.outputStream;
   }
 
   void kill() {
     if (_closed && _pid === null) {
-      if (_onError !== null) {
-        _onError(new ProcessException("Process closed"));
-      }
+      _reportError(new ProcessException("Process closed"));
       return;
     }
     if (_killed) {
       return;
     }
     // TODO(ager): Make the actual kill operation asynchronous.
     if (_kill(_pid)) {
       _killed = true;
       return;
     }
-    if (_onError !== null) {
-      _onError(new ProcessException("Could not kill process"));
-      return;
-    }
+    _reportError(new ProcessException("Could not kill process"));
+    return;
   }
 
   void _kill(int pid) native "Process_Kill";
 
   void close() {
     if (_closed) {
       throw new ProcessException("Process closed");
     }
     _in.close();
     _out.close();
     _err.close();
     _exitHandler.close();
     _closed = true;
   }
 
   void set onExit(void callback(int exitCode)) {
     if (_closed) {
       throw new ProcessException("Process closed");
     }
     if (_killed) {
       throw new ProcessException("Process killed");
     }
     _onExit = callback;
   }
 
-  void set onError(void callback(ProcessException exception)) {
+  void set onError(void callback(e)) {
     _onError = callback;
   }
 
   void set onStart(void callback()) {
     _onStart = callback;
   }
 
+  void _reportError(e) {
+    if (_onError != null) {
+      _onError(e);
+    } else {
+      throw e;
+    }
+  }
+
   String _path;
   ObjectArray<String> _arguments;
   String _workingDirectory;
   List<String> _environment;
   // Private methods of _Socket are used by _in, _out, and _err.
   _Socket _in;
   _Socket _out;
   _Socket _err;
   Socket _exitHandler;
   int _pid;
@@ skipping 97 matching lines @@
 
   void set onStart(void callback()) => _process.onStart = callback;
 
   void set onExit(void callback(int exitCode)) {
     throw new UnsupportedOperationException(
         'Cannot set exit handler on process started with '
         'the run constructor. The exit code will '
         'be supplied in the callback on completion.');
   }
 
-  void set onError(void callback(ProcessException error)) {
+  void set onError(void callback(e)) {
     _process.onError = callback;
   }
 
   void kill() => _process.kill();
 
   void close() => _process.close();
 
   Process _process;
   Function _callback;
   StringBuffer _stdoutBuffer;
   StringBuffer _stderrBuffer;
   int _exitCode;
   bool _stdoutClosed = false;
   bool _stderrClosed = false;
 }