Fix class cast exception on pending tests (EXPOSUREAPP-4909) #2249

* Let NetworkRequestWrapper enforce more specific generics.
No nulls and errors need to be `Throwable`

* Align error dialog generation and remove unnecessary casting.

* Use less specific exception type for `filterIsInstance`.
The expectation is that due to type erase, the filter will let any type of `RequestFailed` through anyways.

Co-authored-by: harambasicluka <64483219+harambasicluka@users.noreply.github.com>
Co-authored-by: Ralf Gehrer <ralfgehrer@users.noreply.github.com>