Error if mongo URL has readPreference, but no readPreferenceTags

[JohannesSoots]

Hi! When passing readPreference in mongo url without readPreferenceTags also in the url then getting following error:

 ** (FunctionClauseError) no function clause matching in String.split/3    
     
     The following arguments were given to String.split/3:
     
         # 1
         []
     
         # 2
         ","
     
         # 3
         []
     
     (elixir 1.14.0) lib/string.ex:479: String.split/3
     (mongodb_driver 1.2.0) lib/mongo/url_parser.ex:241: Mongo.UrlParser.parse_tags/1
     (mongodb_driver 1.2.0) lib/mongo/url_parser.ex:220: Mongo.UrlParser.extend_read_preference_tags/2
     (mongodb_driver 1.2.0) lib/mongo/url_parser.ex:207: Mongo.UrlParser.process_read_preferences/1
     (mongodb_driver 1.2.0) lib/mongo/url_parser.ex:186: Mongo.UrlParser.parse_url/1
     (mongodb_driver 1.2.0) lib/mongo.ex:140: Mongo.start_link/1

Related to #206

[zookzook]

It is fixed in the master branch:
50ea98d

Feel free to check it!

[zookzook]

Closing due to no response.