ON_ERROR
 Trap an error.

Formats
 On_errorstatement
 On_error
  [statement ...]
  [statement ...]
 End_error
 This command is similar to BASIC's ON ERROR goto ... construct, except that the statements to execute when an error occurs are located directly after the ON_ERROR statement. The statement must be executed for the error trap to be enabled. The trap remains enabled after an error occurs. Multiple error traps are allowed in forms and subroutines. Errors will continue to be trapped by the program until a No_error command is issued.

Example
 On_error Goto CALCFAIL
 C = ((B + 1) / A) /B
 On_error
  Error "Record not found"
  Return %ERROR
 End_error
 Get c in DB /Record
 Return
 CALCFAIL:
  Error "Record calculation failed"
  Return %ERROR