Fix https://huntr.dev/bounties/ea181323-51f8-46a2-a60f-6a401907feb7/

app/Repositories/Budget/AvailableBudgetRepository.php

@@ -79,6 +79,14 @@ class AvailableBudgetRepository implements AvailableBudgetRepositoryInterface
 
     }
 
+    /**
+     * @inheritDoc
+     */
+    public function findById(int $id): ?AvailableBudget
+    {
+        return $this->user->availableBudgets->find($id);
+    }
+
     /**
      * Return a list of all available budgets (in all currencies) (for the selected period).
      *