Revert "Return null if no credentials are passed to UserProvider (#21975

)" (#21982)

This reverts commit 3cb0a82.

src/Illuminate/Auth/DatabaseUserProvider.php

@@ -109,10 +109,6 @@ public function retrieveByCredentials(array $credentials)
             }
         }
 
-        if (empty($query->wheres)) {
-            return;
-        }
-
         // Now we are ready to execute the query to see if we have an user matching
         // the given credentials. If not, we will just return nulls and indicate
         // that there are no matching users for these given credential arrays.

src/Illuminate/Auth/EloquentUserProvider.php

@@ -116,10 +116,6 @@ public function retrieveByCredentials(array $credentials)
             }
         }
 
-        if (empty($query->wheres)) {
-            return;
-        }
-
         return $query->first();
     }