fix: cannot provide undefined to useObservable as observable

Author: AndreyShashlovDev

src/react/hook/useObservable.ts

@@ -1,15 +1,15 @@
 import { useEffect, useState } from 'react'
 import { Observable } from 'rxjs'
 
-export function useObservable<T>(observable: Observable<T> | undefined, initialValue: T): T {
+export function useObservable<T>(observable: Observable<T>, initialValue: T): T {
   const [value, setValue] = useState<T>(initialValue)
 
   useEffect(() => {
-    const subscription = observable?.subscribe({
+    const subscription = observable.subscribe({
       next: setValue,
     })
 
-    return () => subscription?.unsubscribe()
+    return () => subscription.unsubscribe()
   }, [observable])
 
   return value