Set regs to stack on return of const_get calls before use

src/vm.c

@@ -702,7 +702,9 @@ mrb_run(mrb_state *mrb, struct RProc *proc, mrb_value self)
     CASE(OP_GETCONST) {
       /* A B    R(A) := constget(Sym(B)) */
       ERR_PC_HOOK(mrb, pc);
-      regs[GETARG_A(i)] = mrb_vm_const_get(mrb, syms[GETARG_Bx(i)]);
+      mrb_value val = mrb_vm_const_get(mrb, syms[GETARG_Bx(i)]);
+      regs = mrb->c->stack;
+      regs[GETARG_A(i)] = val;
       NEXT;
     }
 
@@ -717,7 +719,9 @@ mrb_run(mrb_state *mrb, struct RProc *proc, mrb_value self)
       int a = GETARG_A(i);
 
       ERR_PC_HOOK(mrb, pc);
-      regs[a] = mrb_const_get(mrb, regs[a], syms[GETARG_Bx(i)]);
+      mrb_value val = mrb_const_get(mrb, regs[a], syms[GETARG_Bx(i)]);
+      regs = mrb->c->stack;
+      regs[a] = val;
       NEXT;
     }