Whaaa, still crashes. I tried it first with the updated version (it was already automatically updated from the store), and it crashed.
Then I disconnected Google Drive, still crashed.
After that I uninstalled it and tried to export with a test vault and the sample items - no issues creating the json.
Then I put back the original vault and... it crashed with a 0 bytes json file.
So I guess it's got something to do with the attachments? They are just screenshots and one private key, nothing large or outlandish.