pubsub emulator: Could not construct ApplicationDefaultCredentials

[ollosh]

Everything was working well before with the emulator until I needed to implement a new topic and a subscriber. I went to test old implementation that I'm positive was working, but the exception is the same. I keep getting: Could not construct ApplicationDefaultCredentials which I find weird because I don't think there's any special authentication needed as confirmed by https://cloud.google.com/pubsub/docs/emulator.

I did a bit of digging and I think some code has changed in https://github.com/googleapis/google-cloud-php-pubsub/commit/7f2f17a62b3d2c558f8346b6ac2cd5c34e847a4a, but wanted to check here first if anyone is experiencing the same issue.