Update app.py

app.py

@@ -214,7 +214,7 @@ def test(input_json):
         decay_factors = np.exp(-alpha * DistanceMatrix) * (DistanceMatrix <= threshold)
         
         # for weighted accessibility (e. g. areas)
-        if not destinationWeights.empty:
+        if destinationWeights is not None: #not destinationWeights.empty:
             subdomainsAccessibility = pd.DataFrame(index=DistanceMatrix.index, columns=destinationWeights.columns)
             for col in destinationWeights.columns:
                 subdomainsAccessibility[col] = (decay_factors * destinationWeights[col].values).sum(axis=1)