Update app.py

app.py

@@ -168,10 +168,15 @@ def render_ui():
         # --- TAB 2: Knowledge Graph ---
         with tabs[1]:
             st.markdown("#### Explore Connections")
-            kg_html_path = build_knowledge_graph(results["papers"], results["umls"], results["drug_safety"])
-            with open(kg_html_path, 'r', encoding='utf-8') as f:
-                kg_html = f.read()
-            components.html(kg_html, height=600)
+            try:
+                kg_html_path = build_knowledge_graph(results["papers"], results["umls"], results["drug_safety"])
+                with open(kg_html_path, 'r', encoding='utf-8') as f:
+                    kg_html = f.read()
+                components.html(kg_html, height=600)
+            except Exception as e:
+                st.warning("⚠️ Knowledge graph visualization is unavailable. "
+                           "Please ensure 'pyvis' and 'jinja2' are installed. "
+                           f"Error: {e}")
 
         # --- TAB 3: Visualizations ---
         with tabs[2]: