Clear VM stack in OP_EXEC; ref
MODIFY
src/vm.c
src/vm.c
@@ -2630,6 +2630,7 @@ RETRY_TRY_BLOCK:
pool = irep->pool;
syms = irep->syms;
stack_extend(mrb, irep->nregs);
+ stack_clear(regs+1, irep->nregs-1);
ci->nregs = irep->nregs;
pc = irep->iseq;
JUMP;

Clear VM stack in OP_EXEC; ref #3678