diff --git a/src/TodoistVisualizer.js b/src/TodoistVisualizer.js
index 914537b..a06581e 100644
--- a/src/TodoistVisualizer.js
+++ b/src/TodoistVisualizer.js
@@ -3,6 +3,8 @@ import { Card, CardHeader, CardTitle, CardContent } from '@/components/ui/card';
 import { Checkbox } from '@/components/ui/checkbox';
 import { Input } from '@/components/ui/input';
 import { Button } from '@/components/ui/button';
+import { Alert, AlertDescription, AlertTitle } from '@/components/ui/alert';
+import { AlertCircle, Loader2 } from 'lucide-react';
 
 const TodoistVisualizer = () => {
   const [apiKey, setApiKey] = useState('');
@@ -11,30 +13,56 @@ const TodoistVisualizer = () => {
   const [selectedItems, setSelectedItems] = useState([]);
   const [loading, setLoading] = useState(false);
   const [images, setImages] = useState({});
+  const [error, setError] = useState(null);
+  const [imageGenerating, setImageGenerating] = useState(false);
 
   const fetchTodoistData = async () => {
     setLoading(true);
+    setError(null);
     try {
+      // Validate API key
+      if (!apiKey.trim()) {
+        throw new Error('Please enter your Todoist API key');
+      }
+
+      // Fetch favorites
       const favResponse = await fetch('https://api.todoist.com/rest/v2/favorites', {
         headers: {
           'Authorization': `Bearer ${apiKey}`
         }
       });
+      
+      if (!favResponse.ok) {
+        if (favResponse.status === 401) {
+          throw new Error('Invalid API key. Please check and try again.');
+        }
+        throw new Error('Failed to fetch favorites. Please try again.');
+      }
+      
       const favData = await favResponse.json();
       
+      // Fetch filters
       const filterResponse = await fetch('https://api.todoist.com/rest/v2/filters', {
         headers: {
           'Authorization': `Bearer ${apiKey}`
         }
       });
+
+      if (!filterResponse.ok) {
+        throw new Error('Failed to fetch filters. Please try again.');
+      }
+      
       const filterData = await filterResponse.json();
       
       setFavorites(favData);
       setFilters(filterData);
     } catch (error) {
-      console.error('Error fetching Todoist data:', error);
+      setError(error.message);
+      setFavorites([]);
+      setFilters([]);
+    } finally {
+      setLoading(false);
     }
-    setLoading(false);
   };
 
   const handleItemToggle = (id) => {
@@ -47,11 +75,26 @@ const TodoistVisualizer = () => {
   };
 
   const generateImages = async () => {
-    const newImages = {};
-    selectedItems.forEach(id => {
-      newImages[id] = '/api/placeholder/300/200';
-    });
-    setImages(newImages);
+    setImageGenerating(true);
+    setError(null);
+    try {
+      if (selectedItems.length === 0) {
+        throw new Error('Please select at least one item to visualize');
+      }
+      
+      // Placeholder for image generation
+      const newImages = {};
+      for (const id of selectedItems) {
+        // Simulate API call with delay
+        await new Promise(resolve => setTimeout(resolve, 1000));
+        newImages[id] = '/api/placeholder/300/200';
+      }
+      setImages(newImages);
+    } catch (error) {
+      setError(error.message);
+    } finally {
+      setImageGenerating(false);
+    }
   };
 
   return (
@@ -62,6 +105,14 @@ const TodoistVisualizer = () => {
         </CardHeader>
         <CardContent>
           <div className="space-y-6">
+            {error && (
+              <Alert variant="destructive">
+                <AlertCircle className="h-4 w-4" />
+                <AlertTitle>Error</AlertTitle>
+                <AlertDescription>{error}</AlertDescription>
+              </Alert>
+            )}
+
             <div className="flex gap-4">
               <Input
                 type="password"
@@ -69,17 +120,25 @@ const TodoistVisualizer = () => {
                 value={apiKey}
                 onChange={(e) => setApiKey(e.target.value)}
                 className="flex-1"
+                disabled={loading}
               />
               <Button 
                 onClick={fetchTodoistData}
-                disabled={!apiKey || loading}
+                disabled={loading}
+                className="relative"
               >
+                {loading && (
+                  <Loader2 className="mr-2 h-4 w-4 animate-spin" />
+                )}
                 {loading ? 'Loading...' : 'Fetch Data'}
               </Button>
             </div>
 
             <div className="space-y-4">
               <h3 className="text-lg font-semibold">Favorites</h3>
+              {favorites.length === 0 && !loading && (
+                <p className="text-gray-500">No favorites found. Connect your Todoist account to see your favorites.</p>
+              )}
               <div className="space-y-2">
                 {favorites.map(favorite => (
                   <div key={favorite.id} className="flex items-center space-x-2">
@@ -101,6 +160,9 @@ const TodoistVisualizer = () => {
               </div>
 
               <h3 className="text-lg font-semibold mt-6">Filters</h3>
+              {filters.length === 0 && !loading && (
+                <p className="text-gray-500">No filters found. Create filters in Todoist to see them here.</p>
+              )}
               <div className="space-y-2">
                 {filters.map(filter => (
                   <div key={filter.id} className="flex items-center space-x-2">
@@ -124,10 +186,13 @@ const TodoistVisualizer = () => {
 
             <Button
               onClick={generateImages}
-              disabled={selectedItems.length === 0}
+              disabled={selectedItems.length === 0 || imageGenerating}
               className="mt-4"
             >
-              Generate Images
+              {imageGenerating && (
+                <Loader2 className="mr-2 h-4 w-4 animate-spin" />
+              )}
+              {imageGenerating ? 'Generating Images...' : 'Generate Images'}
             </Button>
           </div>
         </CardContent>
diff --git a/src/components/ErrorAlert.js b/src/components/ErrorAlert.js
new file mode 100644
index 0000000..7c25de7
--- /dev/null
+++ b/src/components/ErrorAlert.js
@@ -0,0 +1,13 @@
+import React from 'react';
+import { Alert, AlertTitle, AlertDescription } from '@/components/ui/alert';
+
+const ErrorAlert = ({ message, onClose }) => {
+  return (
+    <Alert variant="destructive" className="mb-4">
+      <AlertTitle>Error</AlertTitle>
+      <AlertDescription>{message}</AlertDescription>
+    </Alert>
+  );
+};
+
+export default ErrorAlert;
\ No newline at end of file