fix: Workaround for typescript issue #43541 (#3842)

.changeset/short-hats-move.md

@@ -0,0 +1,5 @@
+---
+"mobx-react-lite": patch
+---
+
+Prevent warnings when using `mobx-react-lite` with Rollup

packages/mobx-react-lite/src/useAsObservableSource.ts

@@ -7,7 +7,10 @@ export function useAsObservableSource<TSource extends object>(current: TSource):
         useDeprecated(
             "[mobx-react-lite] 'useAsObservableSource' is deprecated, please store the values directly in an observable, for example by using 'useLocalObservable', and sync future updates using 'useEffect' when needed. See the README for examples."
         )
-    const [res] = useState(() => observable(current, {}, { deep: false }))
+    // We're deliberately not using idiomatic destructuring for the hook here.
+    // Accessing the state value as an array element prevents TypeScript from generating unnecessary helpers in the resulting code.
+    // For further details, please refer to mobxjs/mobx#3842.
+    const res = useState(() => observable(current, {}, { deep: false }))[0]
     runInAction(() => {
         Object.assign(res, current)
     })