Fix exception throwing in connection with process starting.

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 300 matching lines @@
   Function _onError;
   Function _onStart;
 }
 
 
 // _NonInteractiveProcess is a wrapper around an interactive process
 // that restricts the interface to disallow access to the streams and
 // buffers output so it can be delivered to the callback when the
 // process exits.
 class _NonInteractiveProcess implements Process {
-
   _NonInteractiveProcess.start(String path,
                                List<String> arguments,
                                ProcessOptions options,
                                Function this._callback) {
-    _process = new _InteractiveProcess.start(path, arguments, options);
-
-    // Setup process exit handling.
-    _process.onExit = (exitCode) {
-      _exitCode = exitCode;
-      _checkDone();
-    };
-
-    // Extract output encoding options.
+    // Extract output encoding options and verify arguments.
     var stdoutEncoding = Encoding.UTF_8;
     var stderrEncoding = Encoding.UTF_8;
     if (options !== null) {
       if (options.stdoutEncoding !== null) {
         stdoutEncoding = options.stdoutEncoding;
         if (stdoutEncoding is !Encoding) {
           throw new IllegalArgumentException(
               'stdoutEncoding option is not an encoding: $stdoutEncoding');
         }
       }
       if (options.stderrEncoding !== null) {
         stderrEncoding = options.stderrEncoding;
         if (stderrEncoding is !Encoding) {
           throw new IllegalArgumentException(
               'stderrEncoding option is not an encoding: $stderrEncoding');
         }
       }
     }
 
+    // Start the underlying process.
+    _process = new _InteractiveProcess.start(path, arguments, options);
+
+    // Setup process exit handling.
+    _process.onExit = (exitCode) {
+      _exitCode = exitCode;
+      _checkDone();
+    };
+
     // Setup stdout handling.
     _stdoutBuffer = new StringBuffer();
     var stdoutStream = new StringInputStream(_process.stdout, stdoutEncoding);
     stdoutStream.onData = () {
       var data = stdoutStream.read();
       if (data != null) _stdoutBuffer.add(data);
     };
     stdoutStream.onClosed = () {
       _stdoutClosed = true;
       _checkDone();
@@ skipping 56 matching lines @@
   void close() => _process.close();
 
   Process _process;
   Function _callback;
   StringBuffer _stdoutBuffer;
   StringBuffer _stderrBuffer;
   int _exitCode;
   bool _stdoutClosed = false;
   bool _stderrClosed = false;
 }