Refactor: libcib: Assert to satisfy Coverity

Coverity is throwing a CHECKED_RETURN error here, because we check the
return value of cib__get_operation() 4 out of 5 times. However, it was
already checked in file_perform_op_delegate().

Signed-off-by: Reid Wahl <nrwahl@protonmail.com>

Author: nrwahl2

lib/cib/cib_file.c

@@ -154,6 +154,7 @@ process_request(cib_t *cib, xmlNode *request, xmlNode **output)
     // We error checked these in callers
     cib__get_operation(op, &operation);
     op_function = get_op_function(operation);
+    pcmk__assert((operation != NULL) && (op_function != NULL));
 
     rc = pcmk__xe_get_flags(request, PCMK__XA_CIB_CALLOPT, &call_options,
                             cib_none);