Check if m->env is NULL before dereferencing it; fix
MODIFY
src/vm.c
src/vm.c
@@ -1309,7 +1309,9 @@ RETRY_TRY_BLOCK:
else {
stack_extend(mrb, irep->nregs, ci->argc+2);
}
+ if(m->env) {
regs[0] = m->env->stack[0];
+ }
pc = irep->iseq;
JUMP;
}

Check if m->env is NULL before dereferencing it; fix #3436