Prevent circular references

With the drag-n-drop, I can set language hierarchy correctly (Pokomo > Swahili > English). But, what if I want Pokomo (the default) at the top of the list in the language switcher?

Ahh that's a great question, and that really helps me understand where you're coming from - thank you! The order in the switcher block is a separate piece of functionality that can be dealt with separately. hook_language_switch_links_alter() allows specifically adjusting the links in the switcher - including changing their order. I've already got that on clients' sites that I use Language Hierarchy on, because yes, customisations to the language switcher are often needed, which are beyond the scope of what LH can provide. But I can now see how arbitrary language sorting in the way you describe is currently possible as useful for this anyway. So my suggestion of forcing the drag-and-drop for configuring the hierarchy could be unnecessary, if we can address the original problem in another suitable way.

The actual merge request is now very close to being acceptable. We have an open unresolved thread about just getting languages from the existing $languages array instead of loading them again, as getThirdPartySetting() should be available on the configurable language entities there.

Thanks for working hard on this! I'm happy and have set this to merge. If we wanted to improve this further in future, I suggest we find a more efficient way of iterating through all the languages. But at least they won't be repeatedly loaded now, which was my bigger concern.