Fix GC leak in js_proxy_get() (bellard#302)

Fixes bellard#277

Author: xeioex

quickjs.c

@@ -46151,8 +46151,10 @@ static JSValue js_proxy_get(JSContext *ctx, JSValueConst obj, JSAtom atom,
     if (JS_IsException(ret))
         return JS_EXCEPTION;
     res = JS_GetOwnPropertyInternal(ctx, &desc, JS_VALUE_GET_OBJ(s->target), atom);
-    if (res < 0)
+    if (res < 0) {
+        JS_FreeValue(ctx, ret);
         return JS_EXCEPTION;
+    }
     if (res) {
         if ((desc.flags & (JS_PROP_GETSET | JS_PROP_CONFIGURABLE | JS_PROP_WRITABLE)) == 0) {
             if (!js_same_value(ctx, desc.value, ret)) {