Fix running plugins with bad-er world name

[chapulina]

This is a redo of #107, which was reverted in #110.

It now also covers the use case where the worldNames property is not set.

[codecov]

Codecov Report

Merging #111 into ign-gui2 will increase coverage by 0.50%.
The diff coverage is 80.00%.

@@             Coverage Diff              @@
##           ign-gui2     #111      +/-   ##
============================================
+ Coverage     60.43%   60.94%   +0.50%     
============================================
  Files            16       16              
  Lines          2108     2138      +30     
============================================
+ Hits           1274     1303      +29     
- Misses          834      835       +1     

Impacted Files	Coverage Δ
src/plugins/world_control/WorldControl.cc	79.48% <70.00%> (+1.13%)	⬆️
src/plugins/world_stats/WorldStats.cc	97.16% <100.00%> (+2.37%)	⬆️

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[JShep1]

LGTM

[nkoenig]

I think there might still be a problem. I see this error:

[GUI] [Wrn] [WorldControl.cc:173] Ignoring topic [/world/simple_cave_01/stats], world name different from []. Fix or remove your <stats_topic> tag.
Topic [/world//stats] is not valid.
[GUI] [Err] [WorldControl.cc:191] Failed to subscribe to [/world//stats]

[chapulina]

I see this error:

Thanks, you found the one case that I didn't test 🙈 Fixed: 4bfc316

[nkoenig]

Works, thanks!