Change-Id: I9ab95977e5ff37dfa084ff151e666d62cc82d0b9

In many places checking for nullptr is done using EXPECT test macros
that doesn't return from the function when condition is not met
(i.e. they are non-fatal). Lack of further error handling results
in a subsequent segfault. To avoid that in most places it's sufficient
to change macro type to ASSERT.
Signed-off-by: NRobert Drab <robert.drab@huawei.com>

Change-Id: I3ad8064485ced9689f1d13feb27d63d6d96af9cc