ErrorCall is:exact

This is thrown when the user calls error. The String is the argument given to error. Historically, there was a second String for the location, but it was subsumed by the backtrace mechanisms (since base-4.22).
This is thrown when the user calls error. The first String is the argument given to error, second String is the location.
This is thrown when the user calls error. The first String is the argument given to error, second String is the location.