During bootstrapping, the script's name is not necessarily set.

src/isolate.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1382 matching lines @@
         OS::Abort();
       }
     } else if (location != NULL && !location->script().is_null()) {
       // We are bootstrapping and caught an error where the location is set
       // and we have a script for the location.
       // In this case we could have an extension (or an internal error
       // somewhere) and we print out the line number at which the error occured
       // to the console for easier debugging.
       int line_number = GetScriptLineNumberSafe(location->script(),
                                                 location->start_pos());
-      if (exception->IsString()) {
+      if (exception->IsString() && location->script()->name()->IsString()) {
         OS::PrintError(
             "Extension or internal compilation error: %s in %s at line %d.\n",
             *String::cast(exception)->ToCString(),
             *String::cast(location->script()->name())->ToCString(),
             line_number + 1);
-      } else {
+      } else if (location->script()->name()->IsString()) {
         OS::PrintError(
             "Extension or internal compilation error in %s at line %d.\n",
             *String::cast(location->script()->name())->ToCString(),
             line_number + 1);
+      } else {
+        OS::PrintError("Extension or internal compilation error.\n");
       }
     }
   }
 
   // Save the message for reporting if the the exception remains uncaught.
   thread_local_top()->has_pending_message_ = report_exception;
 
   // Do not forget to clean catcher_ if currently thrown exception cannot
   // be caught.  If necessary, ReThrow will update the catcher.
   thread_local_top()->catcher_ = can_be_caught_externally ?
@@ skipping 1101 matching lines @@
 
 #ifdef DEBUG
 #define ISOLATE_FIELD_OFFSET(type, name, ignored)                       \
 const intptr_t Isolate::name##_debug_offset_ = OFFSET_OF(Isolate, name##_);
 ISOLATE_INIT_LIST(ISOLATE_FIELD_OFFSET)
 ISOLATE_INIT_ARRAY_LIST(ISOLATE_FIELD_OFFSET)
 #undef ISOLATE_FIELD_OFFSET
 #endif
 
 } }  // namespace v8::internal