While analyzing gst_vulkan_get_or_create_image_view_with_info() it
seems obvious that this function returns NULL, and that this should be
covered in the return annotations. However, closer inspection indicates
that this is only a precondition check when the incoming arguments are
incompatible with each other, and should not be considered as a function
that optionally returns a pointer.
Signify this by using precondition checks instead of an opencoded
if-return-NULL.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/5736>
006ac293bc