check: add internal errors for unexpected paths

check: add internal errors for unexpected paths

Adding couple INTERNAL_ERROR reports for unwanted parameters:

Ensure the 'top' metadata node cannot be NULL for lvmetad.

Make obvious vginfo2 cannot be NULL.

Report internal error if handler and vg is undefined.

Check for handle in poll_vg().

Ensure seg is not NULL in dev_manager_transient().

Report missing read_ahead for _lv_read_ahead_single().

Check for report handler in dm_report_object().

Check missing VG in _vgreduce_single().