Fixed sort bug when two select values were null (#6493)

Fixes https://github.com/twentyhq/twenty/issues/5762

The problem was only happening with a sort on a select type field, also
appears with currency type and maybe other types.

This was because NULL values were sorted in a random order because the
sort function was comparing two NULL values as not equal, so I just
added a case for when A === B === NULL.

packages/twenty-front/src/utils/sort.ts

@@ -3,7 +3,14 @@ import { Maybe } from '~/generated/graphql';
 export const sortNullsFirst = (
   fieldValueA: Maybe<unknown>,
   fieldValueB: Maybe<unknown>,
-) => (fieldValueA === null ? -1 : fieldValueB === null ? 1 : 0);
+) =>
+  fieldValueA === null && fieldValueB === null
+    ? 0
+    : fieldValueA === null
+      ? -1
+      : fieldValueB === null
+        ? 1
+        : 0;
 
 export const sortNullsLast = (
   fieldValueA: Maybe<unknown>,