fix: add localStorage error handling to theme functionality

- Create safeLocalStorage utility for graceful error handling
- Update useTheme hook to use safeLocalStorage
- Update ThemeControl component to use safeLocalStorage
- Prevents SecurityError when localStorage is unavailable in theme features

This extends the localStorage fix from issue #212 to cover all localStorage usage in the codebase.

lib/src/Components/AppShell/hooks/useTheme.tsx

@@ -1,12 +1,14 @@
 import { useEffect } from 'react'
 
+import { safeLocalStorage } from '#utils/localStorage'
+
 export const useTheme = (defaultTheme = 'default') => {
   useEffect(() => {
-    const savedTheme = localStorage.getItem('theme')
+    const savedTheme = safeLocalStorage.getItem('theme')
     const initialTheme = savedTheme ? (JSON.parse(savedTheme) as string) : defaultTheme
     if (initialTheme !== 'default') {
       document.documentElement.setAttribute('data-theme', defaultTheme)
-      localStorage.setItem('theme', JSON.stringify(initialTheme))
+      safeLocalStorage.setItem('theme', JSON.stringify(initialTheme))
     }
   }, [defaultTheme])
 }

lib/src/Components/Templates/ThemeControl.tsx

@@ -1,5 +1,7 @@
 import { useState, useEffect } from 'react'
 
+import { safeLocalStorage } from '#utils/localStorage'
+
 const themes = [
   'default',
   'light',
@@ -15,14 +17,16 @@ const themes = [
 
 export const ThemeControl = () => {
   const [theme, setTheme] = useState<string>(() => {
-    const savedTheme = localStorage.getItem('theme')
+    const savedTheme = safeLocalStorage.getItem('theme')
     return savedTheme ? (JSON.parse(savedTheme) as string) : 'default'
   })
 
   useEffect(() => {
     if (theme !== 'default') {
-      localStorage.setItem('theme', JSON.stringify(theme))
-    } else localStorage.removeItem('theme')
+      safeLocalStorage.setItem('theme', JSON.stringify(theme))
+    } else {
+      safeLocalStorage.removeItem('theme')
+    }
     document.documentElement.setAttribute('data-theme', theme)
   }, [theme])
 

lib/src/Utils/localStorage.ts

@@ -0,0 +1,32 @@
+/**
+ * Safe localStorage utility that handles SecurityError gracefully
+ * when localStorage is not available (e.g., private browsing mode)
+ */
+export const safeLocalStorage = {
+  getItem: (key: string): string | null => {
+    try {
+      return localStorage.getItem(key)
+    } catch (error) {
+      console.warn(`localStorage.getItem failed for key "${key}":`, error)
+      return null
+    }
+  },
+
+  setItem: (key: string, value: string): void => {
+    try {
+      localStorage.setItem(key, value)
+    } catch (error) {
+      console.warn(`localStorage.setItem failed for key "${key}":`, error)
+      // Silently fail - functionality will work in memory-only mode
+    }
+  },
+
+  removeItem: (key: string): void => {
+    try {
+      localStorage.removeItem(key)
+    } catch (error) {
+      console.warn(`localStorage.removeItem failed for key "${key}":`, error)
+      // Silently fail
+    }
+  },
+}