Fix for issue 25236

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 858 matching lines @@
 
   Heap::Init(result,
              is_vm_isolate
                  ? 0  // New gen size 0; VM isolate should only allocate in old.
                  : FLAG_new_gen_semi_max_size * MBInWords,
              FLAG_old_gen_heap_size * MBInWords,
              FLAG_external_max_size * MBInWords);
 
   // TODO(5411455): For now just set the recently created isolate as
   // the current isolate.
-  Thread::EnterIsolate(result);
+  if (!Thread::EnterIsolate(result)) {
+    // We failed to enter the isolate, it is possible the VM is shutting down,
+    // return back a NULL so that CreateIsolate reports back an error.
+    delete result;
+    return NULL;
+  }
 
   // Setup the isolate message handler.
   MessageHandler* handler = new IsolateMessageHandler(result);
   ASSERT(handler != NULL);
   result->set_message_handler(handler);
 
   // Setup the Dart API state.
   ApiState* state = new ApiState();
   ASSERT(state != NULL);
   result->set_api_state(state);
@@ skipping 1601 matching lines @@
 }
 
 
 RawInstance* IsolateSpawnState::BuildMessage(Thread* thread) {
   return DeserializeObject(thread,
                            serialized_message_, serialized_message_len_);
 }
 
 
 }  // namespace dart