(3)(+0000471): Exception in Document.getDocumentData

(1)(+0000000): {
"name": "Error"
"type": "Google Docs ScriptError"
}

See the last step on Troubleshooting Errors in Word Processor Documents — you'll likely need to make a copy of the document (File → Make a copy) and cut the document down to find the part that's causing the error.