Virtuoso 7.2.12 crashes with the `XENC_GET_KEY_ALGO` function.

Environment: Ubuntu 20.04, docker image `openlink/virtuoso-opensource-7:7.2.12`.

PoC:
```sql
SELECT XENC_GET_KEY_ALGO(NULL);
```

Backtrace:
```
#0 0xdf7b10 (strhash+0x20)
#1 0xdf7453 (id_hash_get+0x33)
#2 0xafc7af (bif_xenc_get_key_algo+0xaf)
#3 0x755af4 (ins_call_bif+0xc4)
#4 0x75d882 (code_vec_run_v+0x25f2)
#5 0x7b9c8f (qn_input+0x38f)
#6 0x7ba136 (qn_send_output+0x236)
#7 0x82c91d (set_ctr_vec_input+0x99d)
#8 0x7b9cce (qn_input+0x3ce)
#9 0x7cb4bb (qr_exec+0x11db)
#10 0x7d8e56 (sf_sql_execute+0x11a6)
#11 0x7d995e (sf_sql_execute_w+0x17e)
#12 0x7e261d (sf_sql_execute_wrapper+0x3d)
#13 0xe29cec (future_wrapper+0x3fc)
#14 0xe315ee (_thread_boot+0x11e)
#15 0x7eff30c6f609 (start_thread+0xd9)
#16 0x7eff30a3f353 (clone+0x43)
```
Virtuoso 7.2.12 crashes with the `XENC_GET_KEY_ALGO` function
This is a GitHub Issue
repo:virtuoso-opensource
owner:openlink
Title : Virtuoso 7.2.12 crashes with the `XENC_GET_KEY_ALGO` function
Issue date:

--- start body ---
Virtuoso 7.2.12 crashes with the `XENC_GET_KEY_ALGO` function.

Environment: Ubuntu 20.04, docker image `openlink/virtuoso-opensource-7:7.2.12`.

PoC:
```sql
SELECT XENC_GET_KEY_ALGO(NULL);
```

Backtrace:
```
#0 0xdf7b10 (strhash+0x20)
#1 0xdf7453 (id_hash_get+0x33)
#2 0xafc7af (bif_xenc_get_key_algo+0xaf)
#3 0x755af4 (ins_call_bif+0xc4)
#4 0x75d882 (code_vec_run_v+0x25f2)
#5 0x7b9c8f (qn_input+0x38f)
#6 0x7ba136 (qn_send_output+0x236)
#7 0x82c91d (set_ctr_vec_input+0x99d)
#8 0x7b9cce (qn_input+0x3ce)
#9 0x7cb4bb (qr_exec+0x11db)
#10 0x7d8e56 (sf_sql_execute+0x11a6)
#11 0x7d995e (sf_sql_execute_w+0x17e)
#12 0x7e261d (sf_sql_execute_wrapper+0x3d)
#13 0xe29cec (future_wrapper+0x3fc)
#14 0xe315ee (_thread_boot+0x11e)
#15 0x7eff30c6f609 (start_thread+0xd9)
#16 0x7eff30a3f353 (clone+0x43)
```
--- end body ---
