Error when model checkpoint and no early stop
Describe the bug
When creating a Trainer, if we set a checkpoint_callback=ModelCheckpoint(...) and early_stop_callback = False we get an error at this line here.
To Reproduce
Steps to reproduce the behavior:

Create a ckpt = ModelCheckpoint(...)
Create a Trainer
Setting checkpoint_callback = ckpt and early_stop_callback=False
See the error AttributeError: 'NoneType' object has no attribute 'wait'

Expected behavior
It should be possible to save the model without setting an EarlyStopping condition. Of course one could set an EarlyStopping with the max integer, but changing the condition from an or to an and solves the problem.
Desktop

OS: Ubuntu 19.04
Browser: Firefox Quantum
Version: 69.0.2