Validate script input

[xhliu]

This locking script can run, but shouldn't bcoz of 2c[0] 21 2c[1]. We can validate here or at bsv.
OP_NOP 21 2c[0] 21 2c[1] OP_0 OP_0 OP_3 OP_0 OP_SUB OP_PICK OP_2 OP_ROLL OP_DROP OP_1 OP_ROLL OP_3 OP_1 OP_SUB OP_PICK OP_1 OP_ROLL OP_DROP OP_NOP OP_1 OP_0 OP_SUB OP_PICK 21 OP_NUMEQUAL OP_VERIFY OP_1 OP_1 OP_SUB OP_PICK 2c OP_NUMEQUAL OP_NIP OP_NIP OP_NIP OP_NIP OP_NIP OP_NIP

[xhliu]

or it contains uninstantiated vars