Importer Rework - GetSectionParent crashes on empty nextPosition

[Robin-Smets]

On a customers machine the rules report crashes, because in some, unforseen cases GetSectionParent tries to perform a Linq operation on null. One part of this issue is to prevent the crash by (one possibiity) make a null check and create a default object on null. But this is not the core of the issue here. It should be investigated why this happens and if it is an issue in HandleRulebaseLinkQueueItem (most likly!).

[abarz722]

I have already started a rework in #3882 because it was crashing for recertification. But review and further rework will be necessary: There are still some unhandled null references, the link type should not be handled with pure database Ids in the plain code (at least an enum should be used) etc.

[Robin-Smets]

It should be possible for @Elutrixx to cherry-pick the relevant commits and continue from there. I am not 100% sure, but that should work without causing merge conflicts when @abarz722 merges #3882 later on.

But something like that could be tested on a new branch in one of your forks.

[Elutrixx]

I can either cherry pick or wait until #3882 is merged and fix any remainings problems, lots of other bugs to fix so I wont get bored :)