Check `ensure` proc is NULL before calling; fix
MODIFY
src/vm.c
src/vm.c
@@ -1351,6 +1351,7 @@ RETRY_TRY_BLOCK:
for (n=0; n<a; n++) {
proc = mrb->c->ensure[epos+n];
mrb->c->ensure[epos+n] = NULL;
+ if (proc == NULL) continue;
irep = proc->body.irep;
ci = cipush(mrb);
ci->mid = ci[-1].mid;

Check `ensure` proc is NULL before calling; fix #3943