Change the error handling in dart:io

runtime/bin/process_impl.dart

Index: runtime/bin/process_impl.dart
diff --git a/runtime/bin/process_impl.dart b/runtime/bin/process_impl.dart
index bb722500b51370f3da49b0102b8bcbcb3c9a8e57..6c11501a837a197a7b9b736980ebb8395eac9883 100644
--- a/runtime/bin/process_impl.dart
+++ b/runtime/bin/process_impl.dart
@@ -166,10 +166,8 @@ class _InteractiveProcess implements Process {
                           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;
 
@@ -242,9 +240,7 @@ class _InteractiveProcess implements Process {
 
   void kill() {
     if (_closed && _pid === null) {
-      if (_onError !== null) {
-        _onError(new ProcessException("Process closed"));
-      }
+      _reportError(new ProcessException("Process closed"));
       return;
     }
     if (_killed) {
@@ -255,10 +251,8 @@ class _InteractiveProcess implements Process {
       _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";
@@ -284,7 +278,7 @@ class _InteractiveProcess implements Process {
     _onExit = callback;
   }
 
-  void set onError(void callback(ProcessException exception)) {
+  void set onError(void callback(e)) {
     _onError = callback;
   }
 
@@ -292,6 +286,14 @@ class _InteractiveProcess implements Process {
     _onStart = callback;
   }
 
+  void _reportError(e) {
+    if (_onError != null) {
+      _onError(e);
+    } else {
+      throw e;
+    }
+  }
+
   String _path;
   ObjectArray<String> _arguments;
   String _workingDirectory;
@@ -409,7 +411,7 @@ class _NonInteractiveProcess implements Process {
         'be supplied in the callback on completion.');
   }
 
-  void set onError(void callback(ProcessException error)) {
+  void set onError(void callback(e)) {
     _process.onError = callback;
   }