Make error class names more consistent.

app/workers/email_receiver_worker.rb

@@ -22,7 +22,7 @@ class EmailReceiverWorker
     reason = nil
 
     case e
-    when Gitlab::Email::Receiver::SentNotificationNotFound
+    when Gitlab::Email::Receiver::SentNotificationNotFoundError
       reason = "We couldn't figure out what the email is in reply to. Please create your comment through the web interface."
     when Gitlab::Email::Receiver::EmptyEmailError
       can_retry = true
@@ -35,7 +35,7 @@ class EmailReceiverWorker
       reason = "You are not allowed to respond to the thread you are replying to. If you believe this is in error, contact a staff member."
     when Gitlab::Email::Receiver::NoteableNotFoundError
       reason = "The thread you are replying to no longer exists, perhaps it was deleted? If you believe this is in error, contact a staff member."
-    when Gitlab::Email::Receiver::InvalidNote
+    when Gitlab::Email::Receiver::InvalidNoteError
       can_retry = true
       reason = e.message
     else

lib/gitlab/email/receiver.rb

@@ -4,13 +4,13 @@ module Gitlab
     class Receiver
       class ProcessingError < StandardError; end
       class EmailUnparsableError < ProcessingError; end
+      class SentNotificationNotFoundError < ProcessingError; end
       class EmptyEmailError < ProcessingError; end
+      class AutoGeneratedEmailError < ProcessingError; end
       class UserNotFoundError < ProcessingError; end
       class UserNotAuthorizedError < ProcessingError; end
       class NoteableNotFoundError < ProcessingError; end
-      class AutoGeneratedEmailError < ProcessingError; end
-      class SentNotificationNotFound < ProcessingError; end
-      class InvalidNote < ProcessingError; end
+      class InvalidNoteError < ProcessingError; end
 
       def initialize(raw)
         @raw = raw
@@ -23,7 +23,7 @@ module Gitlab
       end
 
       def execute
-        raise SentNotificationNotFound unless sent_notification
+        raise SentNotificationNotFoundError unless sent_notification
 
         raise EmptyEmailError if @raw.blank?
 
@@ -53,7 +53,7 @@ module Gitlab
             message << "\n\n- #{error}"
           end
 
-          raise InvalidNote, message
+          raise InvalidNoteError, message
         end
       end