Update app.py

app.py

@@ -1,5 +1,5 @@
 import os
-os.environ['PATH'] += ':/usr/bin'
+import subprocess
 import io
 import base64
 import threading
@@ -21,6 +21,18 @@ import graphviz
 
 logging.basicConfig(level=logging.INFO)
 
+# Update PATH
+os.environ['PATH'] += ':/usr/bin'
+
+# Check Graphviz installation
+try:
+    subprocess.run(['dot', '-V'], check=True, capture_output=True)
+    print("Graphviz is installed and accessible")
+except subprocess.CalledProcessError:
+    print("Error: Graphviz is not accessible")
+except FileNotFoundError:
+    print("Error: Graphviz (dot) is not found in PATH")
+
 openai.api_key = os.getenv("OPENAI_API_KEY")
 if not openai.api_key:
     logging.warning("OPENAI_API_KEY not set. GPT-3.5 model will not be available.")