internal: Add lints for promises (#3733)

* Add lints for floating and misued promises

* Add logging async errors in main

* Add async error catch in test-utils

* Change any to unknown

* Trap promise errors and ignore more await warnings

* Add more ignores and toSync helper

* Fix more lint warnings

* Add more ignores and fixes

* Add more reject reporting

* Add accepting arbitrary parameters to toSync()

* Fix more lints

* Revert unintentional change to non-arrow function

* Revert unintentional change to use arrow function

* Fix new warnings in main with auto updater

* Fix formatting

* Change lints to error

This is what the recommended type checked rules do.

* Fix to properly report promise rejections

* Fix formatting

* Fix formatting

* Remove unused import

* Remove unused convenience function

* Move type helpers

* Fix to not return promise when caller doesn't expect it

* Add ignores to lsp code

src/lib/types.ts

@@ -98,3 +98,18 @@ export function isEnumMember<T extends Record<string, unknown>>(
 export type DeepPartial<T> = {
   [P in keyof T]?: T[P] extends object ? DeepPartial<T[P]> : T[P]
 }
+
+/**
+ * Replace a function's return type with another type.
+ */
+export type WithReturnType<F extends (...args: any[]) => any, NewReturn> = (
+  ...args: Parameters<F>
+) => NewReturn
+
+/**
+ * Assert that a function type is async, preserving its parameter types.
+ */
+export type AsyncFn<F extends (...args: any[]) => any> = WithReturnType<
+  F,
+  Promise<unknown>
+>