DotExpression: Inner when-concrete block sometimes never gets concrete

[alexanderpann]

(links can be followed in maintenance/mps20213)
The mentioned code is this. The main reason are nested dot expressions. Example for such a warning: http://127.0.0.1:63320/node?ref=r%3Aee5b1a89-4907-4bd7-bb79-ba99ef537bd3%28test.ts.expr.os.unitsonly%40tests%29%2F7408964427860868673

As a result, code that asks for the type of a dotExpressions such as dotExpression.type might return null.
Ideally, we only have the equation typeof(de) :==: typeof(de.target). Can we move the additional logic for the option and attempt type to a different place?