Comment 2 for bug 1944546

Have the same problem with ntp rev 47 from charmhub
unit-ntp-10: 09:42:16 WARNING unit.ntp/10.nrpe-external-master-relation-joined File "/var/lib/juju/agents/unit-ntp-10/.venv/lib/python3.6/site-packages/charms/reactive/relations.py", line 716, in set_state
unit-ntp-10: 09:42:16 WARNING unit.ntp/10.nrpe-external-master-relation-joined if self.key not in value['conversations']:
unit-ntp-10: 09:42:16 WARNING unit.ntp/10.nrpe-external-master-relation-joined TypeError: 'NoneType' object is not subscriptable
unit-ntp-10: 09:42:16 ERROR juju.worker.uniter.operation hook "nrpe-external-master-relation-joined" (via explicit, bespoke hook script) failed: exit status 1
unit-ntp-10: 09:42:16 INFO juju.worker.uniter awaiting error resolution for "relation-joined" hook

tried using debug-hook I get the following:

bash: warning: setlocale: LC_ALL: cannot change locale (en_GB.UTF-8)
root@cz21260l6h:~# charms.reactive set_state nrpe-external-master.available
/bin/bash: warning: setlocale: LC_ALL: cannot change locale (en_GB.UTF-8)
Ambiguous possibilities for JUJU_CHARM_DIR; please use --charm or run within a Juju hook context
root@cz21260l6h:~#

The debug-hooks does not go into a session to run the charm.reactive commands.