Better handle network errors such as disconnect / rate limiting.

[nijikokun]

See #57 for more in-depth details.

• 429 currently cause zero values due to items being returned as empty array.
• Network disconnects currently break the requester, which brick the app.

Fixes being implemented:

• 429 now return { status: 429 } so requester can properly debounce queue requests to window timeout
• Network is checked inside of requester threads and queues are debounced when offline.

Future features:

• Notification when network is out
• Check for network on start so you don't have to re-login

Simulation of 429s with console logging on threads:

[nijikokun]

Adding another precaution since reloading the application while rate limited was very destructive previously:

Note this screen will only show if you close the app and re-open while rate-limited, it also does a count-down so you get a visual cue of how many seconds are left.

[nijikokun]

So what happens in beta.9 when you encounter a rate limit?

• Data is returned as empty to the requester.
• Requester sees this, caches it, a portfolio report is built with empty data.
• Reloading while rate-limited causes the application to think you have no tabs
  • This makes it unable to update portfolios
  • Portfolios also zero value out because you are still rate limited.

What will happen in the next release?

• A status report is thrown to the requester
  • Requester debounces the queue based on the timeout interval
  • When it requests again, if it gets another rate-limit it does the debounce again until requests 200 again.
• When you reload and you are rate-limited
  • Before making requests to obtain application data, the application checks your status
    • If you are rate-limited, you see the screen Better handle network errors such as disconnect / rate limiting. #63 (comment)
    • Timeout period is based on how many requests you have attempted, maximum is 4 minutes, minimum is 1 minute periods. These are enforced by GGG. Not me.

[nijikokun]

Fixes can be found in https://github.com/currency-cop/currency-cop/releases/tag/2.0.0-beta.10