fix(SW-441): fixes after PR

hooks/useHash.tsx

@@ -3,22 +3,26 @@
 import { useParams } from "next/navigation"
 import { useEffect, useState } from "react"
 
-function getHash() {
-  if (typeof window === "undefined" || !window.location.hash) {
-    return undefined
-  }
-  return window.location.hash.split("#")[1]
-}
-
 export default function useHash() {
-  const [isClient, setIsClient] = useState(false)
-  const [hash, setHash] = useState(getHash())
+  const [hash, setHash] = useState<string | undefined>(undefined)
   const params = useParams()
 
   useEffect(() => {
-    setIsClient(true)
-    setHash(getHash())
-  }, [params, setHash, setIsClient])
+    const updateHash = () => {
+      const newHash = window.location.hash
+        ? window.location.hash.slice(1)
+        : undefined
+      setHash(newHash)
+    }
 
-  return isClient ? hash : null
+    updateHash()
+
+    window.addEventListener("hashchange", updateHash)
+
+    return () => {
+      window.removeEventListener("hashchange", updateHash)
+    }
+  }, [params])
+
+  return hash
 }

hooks/useScrollSpy.ts

@@ -46,12 +46,9 @@ export default function useScrollSpy(
     const observer = new IntersectionObserver(handleIntersection, mergedOptions)
     const elements = sectionIds
       .map((id) => document.getElementById(id))
-      .filter(Boolean)
+      .filter((el): el is HTMLElement => !!el)
 
     elements.forEach((element) => {
-      if (!element) {
-        return
-      }
       observer.observe(element)
     })