We have a similar issue with mesh objects. Basically the issue is that the active object is in a mode different from the data mode.

To reproduce the issue (although it doesn't crash there) you get two mesh objects, active object is in object mode, and we click on the mesh icon of a second object.
If you resort to the python console you can see that the active object is still in object mode, while the other object is in editmode.

To address this bug we need to understand what should happen when active object is in object mode and we select a data icon (e.g., ebone) for another object in the outliner.

I believe it should make the new object active, and switch to its edit (or pose) mode.
If shift was selected however the previously selected objects could all switch to the mode.

Following is the original conversation I had with @Brecht Van Lommel (brecht) about that:

What should happen when active object (A) is in object mode and we select a data icon (e.g., ebone) for another object (B) in the outliner? Right now it is a bit inconsistent, and leading to crashes

Option A: if both A and B objects are compatible with new suggested edit mode, they both switch to it
Option B: nothin happens (maybe object B is selected, but that's all, we stick to object mode)
Option C: we make object B as active, and switch to its edit (or pose) mode
Option D: dunno, let me focus on something else and go find someone else to bother ;)

For which we agreed that eventually we want outliner and viewport selection to be synced. So then option C would be the right choice. That's for regular click. for shift+click, option A instead.

@Campbell Barton (campbellbarton) @William Reynish (billreynish) any thoughts?

I talked to @Campbell Barton (campbellbarton), his suggestion short-term is to not try to change modes unless current active mode is compatible. Something along the lines of B.

I ended up implementing the solution suggested by @Brecht Van Lommel (brecht) on D4344, pending review.

For the records, I found an old report I created September last year (T56976) which is pretty much a duplicate of this one. It even has its own patch (D3750) though D4344 is more complete.
I will keep pestering my peers this time, so it doesn't fall into the oblivion void once again.