When handling CMD_CRIT error set command_errmsg to NULL after we dump it out,

so that it does not result in error message printed twice.

OK load doodoo
can't find 'doodoo'
can't find 'doodoo'
OK

MFC after:	2 weeks

stand/common/interp_forth.c

@@ -142,6 +142,7 @@ bf_command(FICL_VM *vm)
 	switch (result) {
 	case CMD_CRIT:
 		printf("%s\n", command_errmsg);
+		command_errmsg = NULL;
 		break;
 	case CMD_FATAL:
 		panic("%s", command_errmsg);