Do not allow a hot reload if the isolate has a sticky error

runtime/vm/isolate.cc

 // Copyright (c) 2013, 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.
 
 #include "vm/isolate.h"
 
 #include "include/dart_api.h"
 #include "include/dart_native_api.h"
 #include "platform/assert.h"
 #include "platform/text_buffer.h"
@@ skipping 2174 matching lines @@
       OS::Print(
           "[+%" Pd64 "ms] Isolate %s invoking _runExtension for %s\n",
           Dart::timestamp(), name(), method_name.ToCString());
     }
     result = DartEntry::InvokeFunction(run_extension, arguments);
     if (FLAG_trace_service) {
       OS::Print(
           "[+%" Pd64 "ms] Isolate %s : _runExtension complete for %s\n",
           Dart::timestamp(), name(), method_name.ToCString());
     }
+    // Propagate the error.
     if (result.IsError()) {
-      if (result.IsUnwindError()) {
-        // Propagate the unwind error. Remaining service extension calls
-        // are dropped.
-        return result.raw();
-      } else {
+      // Remaining service extension calls are dropped.
+      if (!result.IsUnwindError()) {
         // Send error back over the protocol.
         Service::PostError(method_name,
                            parameter_keys,
                            parameter_values,
                            reply_port,
                            id,
                            Error::Cast(result));
       }
+      return result.raw();
     }
+    // Drain the microtask queue.
     result = DartLibraryCalls::DrainMicrotaskQueue();
+    // Propagate the error.
     if (result.IsError()) {
+      // Remaining service extension calls are dropped.
       return result.raw();
     }
   }
   return Object::null();
 }
 
 
 RawGrowableObjectArray* Isolate::GetAndClearPendingServiceExtensionCalls() {
   RawGrowableObjectArray* r = pending_service_extension_calls_;
   pending_service_extension_calls_ = GrowableObjectArray::null();
@@ skipping 676 matching lines @@
 void IsolateSpawnState::DecrementSpawnCount() {
   ASSERT(spawn_count_monitor_ != NULL);
   ASSERT(spawn_count_ != NULL);
   MonitorLocker ml(spawn_count_monitor_);
   ASSERT(*spawn_count_ > 0);
   *spawn_count_ = *spawn_count_ - 1;
   ml.Notify();
 }
 
 }  // namespace dart