Error operation
The error operation causes the expression to terminate. When an error block has been defined the function continues with the ON_ERROR block. When no ON_ERROR block has been defined, the expression continues with the FINAL block, when being defined. When no FINAL block has been defined, the execution of the expression terminates and the value of the last statement executed is returned to the calling expression.
You may pass an error code to the ERROR operation, which can be retrieved from the global variable _LastErrorCode .
Definition:
error_op := _error [operand] ';'