INTERNAL ERROR

An INTERNAL ERROR is an error message which indicates that an unexpected condition within the interpreter has occurred. Any appearance of an INTERNAL ERROR (unless it is signalled or otherwise specifically invoked) is an implementation bug. Typically an INTERNAL ERROR is signalled if an "impossible" state has been reached such that it would be unsafe for the interpreter to continue, but the workspace is not expected to be damaged. If the workspace is suspected to be in an unsafe state, a syserror should result instead.