fix: Improve null keywords resulting for topics

app.py

@@ -175,6 +175,7 @@ def generate_plot(
             elif len(cluster_keyword[label]) == 0:
                 cluster_keyword[label] = '-'
             elif len(cluster_keyword[label]) > 1:
+                cluster_keyword[label] = [word for word in cluster_keyword[label] if word != '']
                 cluster_keyword[label] = ', '.join(cluster_keyword[label])
         encoded_labels_keywords = [cluster_keyword[encoded_label] for encoded_label in encoded_labels]
         embeddings_2d = get_tsne_embeddings(embeddings)