Besides the empty SP/MP playername, the empty buddylist from https://code.wildfiregames.com/D209 also triggers this error.
From 2016-05-16:
20:32 < elexis> it's due to the defaults.cfg not having an entry for that
20:37 < elexis> we could just delete that LOGERROR
20:50 < elexis> it was added in r15980
20:50 < WildfireBot> r15980. Author: leper. Commit message: Use an FSM to parse our config files instead of using CParser. Refs <a class="closed ticket" href="/ticket/2589" title="task: Remove CParser (closed: fixed)">#2589</a>. Print error messages if we encountered an invalid setting. http://trac.wildfiregames.com/changeset/15980
20:51 <@leper> removing it works, but hides the fact that a higher priority config file cannot delete settings by just setting it to ""
20:52 <@leper> which is the reason this message exists
20:54 < elexis> so it would overwrite the config value with emptystring
20:54 < elexis> not sure if we need a warning / error msg for that
21:14 <@leper> elexis: nope, it ignores the setting
21:15 <@leper> elexis: as it would ignore the last line otherwise I think it should stay
21:15 <@leper> and if people edit the config file manually (which they shouldn't have to) then they should fix warnings they cause
21:15 < elexis> ah, so if default.cfg has foo="bar" and user.cfg has foo="" it would yield foo="bar"? hm
21:17 <@leper> very likely, check the code to be sure
From 2016-05-19:
14:31 <@leper> if someone else fixes all the issues that will arise, meh
14:31 <@leper> if not, no
14:31 < elexis> which issues would arise?
14:31 < elexis> if the config file specifies empty string, it should load empty string, no?
14:31 <@leper> what happens if code expects a setting to actually be there?
14:32 <@leper> and being set to something
14:32 < elexis> then that function should be fixed
14:34 <@leper> likely, but then again there are likely countless places that will break in one way or another from someone feeding you bogus config data
14:34 <@leper> (which shouldn't be any more trusted than any other user input, which is why the config parser is conservative in accepting data
14:34 <@leper> )
14:40 < elexis> the users of config values shouldnt rely on not getting an empty string, I can check many occurances. (there are probably many cases for broken user data which are not checked also)
14:43 <@leper> true, but you have to start somewhere
14:44 < elexis> start: the user cant break anything from the GUI :P
14:46 <@leper> fix: check if a config setting exists before using it?
14:47 <@leper> (or unassign me from config related tickets and do whatever if I don't have to bother about any bugs arising from that)
From 2016-06-15:
17:14 <@leper> #3990 I still don't think that is the way to go, but if someone wants to handle and be responsible for all the bugs that will cause, meh
