Fix committed to master branch: http://bugs.limesurvey.org/plugin.php?page=Source/view&id=27758

also this fix:
https://github.com/LimeSurvey/LimeSurvey/commit/295af546cb9a2d80f4ae921a4e79a3ecfa9f608a

First commit is the real fix. But it will be applied only to new installation, or if you reset your themes after update (but then you'll lose your specific configuration for options)

With the second commit, not existing files are not registered anymore: so no more errors, even if you don't reset your themes.
But, if you turn on debug mode in config.php and front end console error in global settings: you'll still have a nice console exception saying that your theme config is somehow wrong.

also, to makes things more clear, to avoid those kind of mistakes in the future:

https://github.com/LimeSurvey/LimeSurvey/commit/920160d02befdb00f96c24610f25cd82e33ba824

https://github.com/LimeSurvey/LimeSurvey/commit/b6c4ce0658208c697ab88da51b8dba7ed2a86995

https://github.com/LimeSurvey/LimeSurvey/commit/1b5890adbc8a82355d3f52104f69fbd003188b62

Fix committed to master branch: http://bugs.limesurvey.org/plugin.php?page=Source/view&id=27764

With last commit:

Now, files are added to the parent theme where the file exist. So it avoid many possible issue, that's why many notes disappeared.
It also means that a wrong config.xml adding a file that doesn't need to be added will not cause any error...

Indeed, what was a bug before (adding a file that doesn't exist locally and that already exists in a parent theme ) become now a functionality: it give the possibility to reorder the file loading of any theme from any theme.

Version 3.14.8+180829 released