Check the type of $message in Validation::errors() to prevent issues …

…when a field name and rule are the same, fixes #4365

classes/kohana/validation.php

@@ -542,19 +542,19 @@ public function errors($file = NULL, $translate = TRUE)
 				}
 			}
 
-			if ($message = Kohana::message($file, "{$field}.{$error}"))
+			if ($message = Kohana::message($file, "{$field}.{$error}") AND is_string($message))
 			{
 				// Found a message for this field and error
 			}
-			elseif ($message = Kohana::message($file, "{$field}.default"))
+			elseif ($message = Kohana::message($file, "{$field}.default") AND is_string($message))
 			{
 				// Found a default message for this field
 			}
-			elseif ($message = Kohana::message($file, $error))
+			elseif ($message = Kohana::message($file, $error) AND is_string($message))
 			{
 				// Found a default message for this error
 			}
-			elseif ($message = Kohana::message('validation', $error))
+			elseif ($message = Kohana::message('validation', $error) AND is_string($message))
 			{
 				// Found a default message for this error
 			}