Discarded futures are not reported in code analysis

[limwa]

This does bring another question to mind: don't we have a "unawaited_futures" lint enabled? If yes, why wasn't this caught earlier?

Originally posted by @limwa in #1365 (comment)

The reason the problem was not caught earlier is that the unawaited_futures lint only applies to async functions. To have the same effect in non-async functions, we can try enabling the discarded_futures in the code analysis and check if the problems reported by it are real problems or not (in other words, check if the lint rule is effective on our codebase).

[limwa]

Upon further analysis, discarded_futures would not catch the error in #1365, so I'm not sure what else we can do...

[limwa]

I have created an issue in the Dart issue tracker to see if this is an issue they are looking to fix in the Dart analyzer or not. If they are interested in having it fixed, I can look into contributing an update to the lint rules with a PR to the Dart SDK.

The issue is available here: dart-lang/sdk#56921