Improve user experience around HTTP requests performed by Explorer #4
Description
When working with the explorer, the end-user is not aware of HTTP operations happening in the background.
- I wasn't aware that I had to hit "Enter" to fetch the resource when changing the URL.
- When I was on the plane WiFi and received a timeout, I had no idea the Explorer broke
- When I passed an invalid URL which returned a 404, there was no messaging to alert me
- Parsing of the JSON API doc occurs even if it isn't a valid doc (404/403/502) and is a text response.