Research: Handle 500s

[cavis]

When an RSS url returns a 500 (or a connection timeout as recently seen)... we should:

• Log a warning (so we can track in CloudWatch)
• Return a 200 to the user (or a different non-5XX?)
• Render a nice error message for the user

That way we get visibility into these, but don't have to sift through a bunch of 5XX alarms on our side.

[cavis]

Update: these 500s are coming from our own proxy. So the frontend is requesting the proxy, and the proxy gets an ECONNRESET or somethnig.

[cavis]

Update 2: this is now a research. Can we track these down? If not, can we have the client retry the proxy request a couple times?