diff --git a/frontend/src/features/vault/components/CategoryManager.tsx b/frontend/src/features/vault/components/CategoryManager.tsx
index f94c162..dd67b3d 100644
--- a/frontend/src/features/vault/components/CategoryManager.tsx
+++ b/frontend/src/features/vault/components/CategoryManager.tsx
@@ -382,7 +382,7 @@ const CategoryManager: React.FC = () => {
         {/* Categories Grid/List */}
         {!isLoading && filteredCategories.length > 0 && (
           <div className="space-y-10">
-            {filteredCategories.map((category) => (
+            {(filteredCategories ?? []).map((category) => (
               <CategorySection
                 key={category.id}
                 category={category}
@@ -825,7 +825,7 @@ const OrganizationModal: React.FC<OrganizationModalProps> = ({
                 ) : (
                   <div className="w-full h-full bg-gradient-to-br from-zinc-200 to-zinc-300 dark:from-zinc-700 dark:to-zinc-800 rounded-lg flex items-center justify-center">
                     <span className="text-zinc-500 dark:text-zinc-400 font-bold text-2xl">
-                      {newOrg.name ? newOrg.name.charAt(0).toUpperCase() : '?'}
+                      {newOrg.name ? newOrg.name[0].toUpperCase() : '?'}
                     </span>
                   </div>
                 )}
diff --git a/frontend/src/features/vault/components/OrganizationCard.tsx b/frontend/src/features/vault/components/OrganizationCard.tsx
index 2b9d3dc..68a89b1 100644
--- a/frontend/src/features/vault/components/OrganizationCard.tsx
+++ b/frontend/src/features/vault/components/OrganizationCard.tsx
@@ -186,7 +186,7 @@ const OrganizationCard: React.FC<OrganizationCardProps> = ({ org, onDelete, onEd
           // Fallback: First letter
           <div className="w-12 h-12 sm:w-14 sm:h-14 bg-gradient-to-br from-blue-500/20 to-blue-600/10 border border-blue-500/20 rounded-lg sm:rounded-xl flex items-center justify-center">
             <span className="text-lg sm:text-xl font-bold text-blue-400">
-              {org.name.charAt(0).toUpperCase()}
+              {org.name[0].toUpperCase()}
             </span>
           </div>
         )}
diff --git a/frontend/src/features/vault/components/VaultListItem.tsx b/frontend/src/features/vault/components/VaultListItem.tsx
index 836d11e..bf2ec30 100644
--- a/frontend/src/features/vault/components/VaultListItem.tsx
+++ b/frontend/src/features/vault/components/VaultListItem.tsx
@@ -168,7 +168,7 @@ const VaultListItem: React.FC<VaultListItemProps> = ({ org, onClick, onEdit, onD
         ) : (
           <div className="w-8 h-8 sm:w-10 sm:h-10 bg-gradient-to-br from-blue-500/20 to-blue-600/10 border border-blue-500/20 rounded-lg flex items-center justify-center">
             <span className="text-sm sm:text-base font-bold text-blue-400">
-              {org.name.charAt(0).toUpperCase()}
+              {org.name[0].toUpperCase()}
             </span>
           </div>
         )}
diff --git a/frontend/src/features/vault/hooks/useExport.ts b/frontend/src/features/vault/hooks/useExport.ts
index 6c294c0..4e19b88 100644
--- a/frontend/src/features/vault/hooks/useExport.ts
+++ b/frontend/src/features/vault/hooks/useExport.ts
@@ -148,7 +148,7 @@ export function useExport(): UseExportReturn {
    */
   const exportVault = useCallback(async (password: string, format: ExportFormat) => {
     // Validate inputs
-    if (!password || password.trim() === '') {
+    if (!password || password.trim().length === 0) {
       setError('Password is required');
       setPhase('ERROR');
       return;
@@ -225,7 +225,7 @@ export function useExport(): UseExportReturn {
       setProgressMessage(`Found ${orgIds.length} organizations...`);
       
       // Fetch all profiles from all organizations in parallel
-      const profilePromises = orgIds.map(orgId =>
+      const profilePromises = (orgIds ?? []).map(orgId =>
         apiClient.get<EncryptedProfile[]>(`/organizations/${orgId}/profiles/`)
           .then(res => ({ orgId, profiles: res.data }))
           .catch(() => ({ orgId, profiles: [] }))
diff --git a/frontend/src/utils/encryption.ts b/frontend/src/utils/encryption.ts
index 9cd0d47..f766aa7 100644
--- a/frontend/src/utils/encryption.ts
+++ b/frontend/src/utils/encryption.ts
@@ -128,7 +128,7 @@ export async function encryptData(
   plaintext: string,
   key: CryptoKey
 ): Promise<{ iv: string; ciphertext: string }> {
-  if (!plaintext || plaintext.trim() === '') {
+  if (!plaintext || plaintext.trim().length === 0) {
     throw new Error('Cannot encrypt empty data');
   }
 
@@ -269,7 +269,7 @@ export async function decryptCredentialFields(
   type IvKey = `${FieldName}_iv`;
   
   // Decrypt all fields in parallel for better performance
-  const decryptionPromises = fieldNames.map(async (fieldName) => {
+  const decryptionPromises = (fieldNames ?? []).map(async (fieldName) => {
     const encryptedKey = `${fieldName}_encrypted` as EncryptedKey;
     const ivKey = `${fieldName}_iv` as IvKey;
     const ciphertext = encryptedData[encryptedKey];