Correctly json_encode validation errors.

app/Repositories/APIRepository.php

@@ -141,7 +141,7 @@ class APIRepository
         // Run validator, throw catchable and displayable exception if it fails.
         // Exception includes a JSON result of failed validation rules.
         if ($validator->fails()) {
-            throw new DisplayValidationException($validator->errors());
+            throw new DisplayValidationException(json_encode($validator->errors()));
         }
 
         DB::beginTransaction();