fix null filter bug

src/App.svelte

@@ -50,9 +50,10 @@
   }
 
   function handleClearFilter(e) {
-    filter = null
-    shownNotes = notes
-    storage.saveFilter(null)
+    filter = ''
+    shownNotes = applyFilterSort(notes, '')
+
+    storage.saveFilter('')
   }
 
   function handleToggleDarkMode(e) {

src/storage.js

@@ -3,10 +3,10 @@ export default class Storage {
 		this.prefix = "notesapp"
 	}
 
-	getFilter = () => this.#load('filter', null)
+	getFilter = () => this.#load('filter')
 	saveFilter = (filter) => this.#save('filter', filter)
 
-	getTheme = () => this.#load('theme', '')
+	getTheme = () => this.#load('theme')
 	saveTheme = (theme) => this.#save('theme', theme)
 
 	getNotes() {
@@ -24,7 +24,7 @@ export default class Storage {
 		localStorage.setItem(`${this.prefix}-${key}`, value)
 	}
 
-	#load(key, defaultValue = null) {
+	#load(key, defaultValue = '') {
 		const value = localStorage.getItem(`${this.prefix}-${key}`) || defaultValue
 		console.log(`loading key '${key}' with value '${value}'`)
 		return value