fix: guard against malformed API response and empty matches list

plants/services/plantnet.py

@@ -53,6 +53,7 @@ def identify(images):
     if not results:
         raise PlantNetError('No match found — try a different photo or organ.')
 
+    try:
         return [
             {
                 'scientific_name': r['species']['scientificNameWithoutAuthor'],
@@ -64,3 +65,5 @@ def identify(images):
             }
             for r in results[:5]
         ]
+    except (KeyError, TypeError) as exc:
+        raise PlantNetError('Unexpected API response format.') from exc

plants/views/identify.py

@@ -63,6 +63,8 @@ def identify_confirm(request):
         return redirect('identify_upload')
 
     matches = request.session['identify_matches']
+    if not matches:
+        return redirect('identify_upload')
 
     if request.method == 'POST':
         try: