[O2B-1506] Fix logic in greaterThanOrNull and lowerThanOrNull methods

Corrected the logic in QueryBuilder's greaterThanOrNull and lowerThanOrNull methods when the notFlag is set.

Author: isaachilly

lib/database/utilities/QueryBuilder.js

@@ -155,7 +155,7 @@ class WhereQueryBuilder {
     greaterThanOrNull(min, strict) {
         if (this.notFlag) {
             this.notFlag = !this.notFlag;
-            this.lowerThanOrNull(min, !strict);
+            this.lowerThan(min, !strict);
             this.notFlag = !this.notFlag;
             return;
         }
@@ -179,7 +179,7 @@ class WhereQueryBuilder {
     lowerThanOrNull(max, strict) {
         if (this.notFlag) {
             this.notFlag = !this.notFlag;
-            this.greaterThanOrNull(max, !strict);
+            this.greaterThan(max, !strict);
             this.notFlag = !this.notFlag;
             return;
         }