Increase the chance of printing a useful error when bootstrapping fails

src/pending-compilation-error-handler.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/pending-compilation-error-handler.h"
 
 #include "src/debug.h"
 #include "src/handles.h"
 #include "src/isolate.h"
 #include "src/messages.h"
@@ skipping 23 matching lines @@
       error = factory->NewError("MakeReferenceError", message_, argument);
       break;
     case kSyntaxError:
       error = factory->NewError("MakeSyntaxError", message_, argument);
       break;
     default:
       UNREACHABLE();
       break;
   }
 
+  if (!error->IsJSObject()) {
+    isolate->Throw(*error, &location);
+    return;
+  }
+
   Handle<JSObject> jserror = Handle<JSObject>::cast(error);
 
   Handle<Name> key_start_pos = factory->error_start_pos_symbol();
   JSObject::SetProperty(jserror, key_start_pos,
                         handle(Smi::FromInt(location.start_pos()), isolate),
                         SLOPPY).Check();
 
   Handle<Name> key_end_pos = factory->error_end_pos_symbol();
   JSObject::SetProperty(jserror, key_end_pos,
                         handle(Smi::FromInt(location.end_pos()), isolate),
                         SLOPPY).Check();
 
   Handle<Name> key_script = factory->error_script_symbol();
   JSObject::SetProperty(jserror, key_script, script, SLOPPY).Check();
 
   isolate->Throw(*error, &location);
 }
 }  // namespace internal
 }  // namespace v8