We need to improve this error as it is currently very obscure and hard to track down.

My suggestion would be to turn it into a $log warning that doesn't throw an error but still prints a stack trace.

Could we make it so that anything that would eventually trigger a $digest cycle check for $$phase at their entry point, and then have them print a warning and return?

If not, in which ways do you believe we could improve the traceability of $digest invocation overlaps?

_{Refer to this StackOverflow question for background}