Error while refreshing charm when Mjolnir is enabled

[amandahla]

Bug Description

The following happens:

2023-10-19T13:17:15.284Z [container-agent] The above exception was the direct cause of the following exception:
2023-10-19T13:17:15.284Z [container-agent] 
2023-10-19T13:17:15.284Z [container-agent] Traceback (most recent call last):
2023-10-19T13:17:15.284Z [container-agent]   File "/var/lib/juju/agents/unit-synapse-0/charm/./src/charm.py", line 179, in <module>
2023-10-19T13:17:15.284Z [container-agent]     main(SynapseCharm)
2023-10-19T13:17:15.284Z [container-agent]   File "/var/lib/juju/agents/unit-synapse-0/charm/venv/ops/main.py", line 443, in main
2023-10-19T13:17:15.284Z [container-agent]     ops.charm._evaluate_status(charm)
2023-10-19T13:17:15.284Z [container-agent]   File "/var/lib/juju/agents/unit-synapse-0/charm/venv/ops/charm.py", line 1105, in _evaluate_status
2023-10-19T13:17:15.284Z [container-agent]     charm.on.collect_unit_status.emit()
2023-10-19T13:17:15.284Z [container-agent]   File "/var/lib/juju/agents/unit-synapse-0/charm/venv/ops/framework.py", line 342, in emit
2023-10-19T13:17:15.284Z [container-agent]     framework._emit(event)
2023-10-19T13:17:15.284Z [container-agent]   File "/var/lib/juju/agents/unit-synapse-0/charm/venv/ops/framework.py", line 839, in _emit
2023-10-19T13:17:15.284Z [container-agent]     self._reemit(event_path)
2023-10-19T13:17:15.284Z [container-agent]   File "/var/lib/juju/agents/unit-synapse-0/charm/venv/ops/framework.py", line 928, in _reemit
2023-10-19T13:17:15.284Z [container-agent]     custom_handler(event)
2023-10-19T13:17:15.284Z [container-agent]   File "/var/lib/juju/agents/unit-synapse-0/charm/src/mjolnir.py", line 157, in _on_collect_status
2023-10-19T13:17:15.284Z [container-agent]     self.enable_mjolnir()
2023-10-19T13:17:15.284Z [container-agent]   File "/var/lib/juju/agents/unit-synapse-0/charm/src/mjolnir.py", line 210, in enable_mjolnir
2023-10-19T13:17:15.284Z [container-agent]     mjolnir_user = actions.register_user(
2023-10-19T13:17:15.284Z [container-agent]   File "/var/lib/juju/agents/unit-synapse-0/charm/src/actions/register_user.py", line 76, in register_user
2023-10-19T13:17:15.284Z [container-agent]     raise RegisterUserError(str(exc)) from exc
2023-10-19T13:17:15.284Z [container-agent] actions.register_user.RegisterUserError: HTTP error from http://localhost:8008/_synapse/admin/v1/register.
2023-10-19T13:17:15.546Z [container-agent] 2023-10-19 13:17:15 ERROR juju.worker.uniter.operation runhook.go:153 hook "update-status" (via hook dispatching script: dispatch) failed: exit status 1

To Reproduce

juju deploy synapse
juju config synapse enable_mjolnir=true
juju refresh synapse

Environment

latest/edge

Relevant log output

Already provided in the description

Additional context

No response