Currently when you press 'Call Backend' the page crashes because backendResponse was not 200 OK. I should have some simple handling for this, such that: 1. The network request is made within Go code instead of bouncing back and forth between Go and a JS Fetch wrapper. 2. If the remote network is unreachable, throw an error instead of panicing 3. If the remote network is unreachable, throw up a warning banner like the 'we just quit WASM' warning banner which says a network request failed or whatever.