Retries on Service Unavailable
Sometimes servers or proxy may return a [503 Service Unavailable](https://www.webfx.com/web-development/glossary/http-status-codes/what-is-a-503-status-code/) or [504 Gateway Timeout](https://www.webfx.com/web-development/glossary/http-status-codes/what-is-a-504-status-code/).
When it happens on a JSON-RPC request, the current actions (usually the tab) can no more be trusted (and thus be used). But as such error may be temporary, we should retry the request a few times before failing. The headers may contain a `Retry-After` value which define the delay to wait but I think we should try earlier if the value is too long for the user to wait.
issue