The PHP files in the BiblioPlus extension have a mix of space and tab indents.

These should be normalised to being all tabs instead of spaces.

It's a bone of contention in the Open Source community whether tabs or spaces are "better". The main thing here for us, is to be at a minimum consistent, using the projects style consistently throughout the extension.

https://www.mediawiki.org/wiki/Manual:Coding_conventions
https://www.mediawiki.org/wiki/Manual:Coding_conventions/PHP