fix rubocop Style/EmptyElse cop

.rubocop_rubyzip.yml

@@ -110,10 +110,6 @@ Style/CommentIndentation:
 Style/Documentation:
   Enabled: false
 
-# Offense count: 3
-Style/EmptyElse:
-  Enabled: false
-
 # Offense count: 1
 # Configuration parameters: EnforcedStyle, SupportedStyles.
 Style/FormatString:

lib/zip/entry_set.rb

@@ -32,8 +32,6 @@ module Zip
     def delete(entry)
       if @entry_set.delete(to_key(entry))
         entry
-      else
-        nil
       end
     end
 

lib/zip/filesystem.rb

@@ -328,8 +328,6 @@ module Zip
           e.extra['UniversalTime'].atime
         elsif e.extra.member? 'NTFS'
           e.extra['NTFS'].atime
-        else
-          nil
         end
       end
 
@@ -339,8 +337,6 @@ module Zip
           e.extra['UniversalTime'].ctime
         elsif e.extra.member? 'NTFS'
           e.extra['NTFS'].ctime
-        else
-          nil
         end
       end