refactor(streamingRequest): internal method for request functions

- TS package type inference for request functions.
- Type fix for Lua's waitFor callback.
- Lua request functions cannot return nil.

imports/waitFor/shared.lua

@@ -1,6 +1,6 @@
 ---Yields the current thread until a non-nil value is returned by the function.
 ---@generic T
----@param cb fun(): T
+---@param cb fun(): T?
 ---@param errMessage string?
 ---@param timeout? number | false Error out after `~x` ms. Defaults to 1000, unless set to `false`.
 ---@return T