Google Maps API 發生 DeletedApiProjectMapError 時:

You need to enable both the Google Maps Javascript API, and the Geocoding API.

https://console.developers.google.com/projectselector/apis/library

and

https://console.developers.google.com/projectselector/apis/api/geocoding_backend

Afterwards the error was RefererNotAllowedMapError instead of DeletedApiProjectMapError, but that was because I was running it on localhost - and it worked on the actual site after I added the domain in Credentials -> Domain Verification