fix(query): undefined data in _groupJoinData #9141

lib/dialects/abstract/query.js

@@ -613,10 +613,10 @@ class AbstractQuery {
             length = $keyPrefix.length;
             if (length) {
               for (i = 0; i < length; i++) {
-                if (i === length -1) {
+                if (i === length - 1) {
                   values = $current[$keyPrefix[i]] = {};
                 }
-                $current = $current[$keyPrefix[i]];
+                $current = $current[$keyPrefix[i]] || {};
               }
             }
           }