error in process filter: HTTP Error: 502, "Bad gateway"
This is a frequently occurring error. Adding some formatting the full error is:
error in process filter: ghub--signal-error: HTTP Error: 502, "Bad gateway", "/graphql", ((data . "null") (errors ((message . "Something went wrong while executing your query. This may be the result of a timeout, or it could be a GitHub bug. Please include `CC2C:4FEA:A1771C1:CBF40CE:5C33F7E5` when reporting this issue."))))
This indicates that something went wrong within Github’s network. See https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#5xx_server_errors. The appended error message also says as much: "This may be the result of a timeout, or it could be a GitHub bug."
It appears that this happens more often in big repositories, especially during the initial pull, but this may be an illusion; it is known to also happens for smaller, incremental requests.
I believe that more data just means more requests and thus more opportunities for things to go wrong. It seems unlikely that this is due to us requesting too much data at once (in that case we would get a different error from GraphQL, not HTTP). When fetching lots of data, then we do not request one large response but make many requests and we then collect the many responses (pagination forces us to do that).
The timeout may be due to many requests from other people arriving at some Github-internal bottleneck at the same time, or it may be due to cold caches and overly aggressive timeouts. We just don’t know; it’s their infrastructure.
The second problem is that we currently simply error out if we get this error. This could be changed and eventually it will be, but for the time being your only option is to just try again, possibly repeatedly and possibly after a delay to give whatever congestion may exist on the other end a chance to clear or to give their caches a chance to warm up.
This was also discussed in https://github.com/magit/forge/issues/20 and https://github.com/magit/ghub/issues/83.