RAP-483 Improve diagnostics

RAP-483 appeared to be a bug, investigation showed the behaviour was intended. Improving the diagnostics to avoid the confusion.

Fixes some issues regarding uninitialized members. These errors caused tests to randomly fail.

Fixes some compiler diagnostics.

requested review from @dijkema

assigned to @wever

approved this merge request

mentioned in commit 87b88a7e

merged

mentioned in merge request !1343 (merged)