Z2M crashes when it cannot save the state

[syphernl]

What happened

Because of the issues in #4307 I switched to the dev-branch. However, it crashes every 5 minutes.
supervise-daemon restarts the process and 5 minutes later it happens again.

The last line of each log was Saving state to file /opt/zigbee2mqtt/data/state.json. I looked in to this and found out that that file was not writable for the Z2M user.

What did you expect to happen

An error to be shown that the state could not be saved and Z2M not to crash / exit because it cannot write to the state file.

How to reproduce it (minimal and precise)

• Ensure the data/state.json is not writable for the Z2M user (in my case it was root:root with 0644 permissions while Z2M runs as zigbee2mqtt user)
• Start Z2M
• After 5 minutes Z2M will stop with exit code 1.

Debug info

Zigbee2MQTT version: 1.14.4-dev (9c2fd10)
Adapter hardware: CC2531
Adapter firmware version: 20190619

[Koenkk]

Fixed!

Changes will be available in the latest dev branch in a few hours (https://www.zigbee2mqtt.io/how_tos/how-to-switch-to-dev-branch.html)