Add check for cu_exists_f1_ue_data() before calling cu_get_f1_ue_data()
to prevent assertion failure when telnet command 'ci fetch_du_by_ue_id'
is used for UEs that have been handed over via N2 (and no longer have
F1 UE data).
This fixes the crash:
Assertion (ret == HASH_TABLE_OK && data != ((void *)0)) failed!
In get_hashtable_data() /oai-ran/openair2/F1AP/f1ap_ids.c:36
element for ue_id 1 not found
The function now returns NULL gracefully when F1 UE data is not available.
Co-authored-by: Guido Casati <hello@guidocasati.com>
