ErrorCall package:ghc-internal

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).
Deprecated: ErrorCallWithLocation has been deprecated in favour of ErrorCall (which does not have a location). Backtraces are now handled by the backtrace exception mechanisms exclusively.