Fix Lint/RescueWithoutErrorClass

Author: tamird

.rubocop_todo.yml

@@ -46,11 +46,6 @@ Lint/AmbiguousBlockAssociation:
   Exclude:
     - 'spec/mysql2/client_spec.rb'
 
-# Offense count: 1
-Lint/RescueWithoutErrorClass:
-  Exclude:
-    - 'lib/mysql2/em.rb'
-
 # Offense count: 2
 # Cop supports --auto-correct.
 Lint/UnifiedInteger:

lib/mysql2/em.rb

@@ -17,7 +17,7 @@ def notify_readable
           detach
           begin
             result = @client.async_result
-          rescue => e
+          rescue StandardError => e
             @deferable.fail(e)
           else
             @deferable.succeed(result)