Cannot add address using form, HTTP 500

[PeteDevoy]

Not sure if anyone maintaining the services still but:
https://alpha.openaddressesuk.org/get-involved/add-an-address
POSTs to:
https://sorting-office.openaddressesuk.org/address
but 500 with response body simply:

<h1>Internal Server Error</h1>

On another note, would be interesting to know what the site stats are, e.g. how much interest there is despite the project being in hibernation.

Edit: just seen related #60