error handling

app.py

@@ -18,20 +18,28 @@ def loading_pdf():
     return "Working on the upload. Also, pondering the usefulness of sporks..."
 
 def pdf_changes(pdf_doc):
-    loader = OnlinePDFLoader(pdf_doc.name)
-    documents = loader.load()
-    text_splitter = CharacterTextSplitter(chunk_size=1000, chunk_overlap=100)
-    texts = text_splitter.split_documents(documents)
-    embeddings = OpenAIEmbeddings()
-    global db
-    db = Chroma.from_documents(texts, embeddings)
-    retriever = db.as_retriever()
-    global qa 
-    qa = ConversationalRetrievalChain.from_llm(
-        llm=OpenAI(temperature=0.2, model_name="gpt-3.5-turbo", max_tokens=-1, n=2),  
+     try:
+        if pdf_doc is None:
+            return "No PDF uploaded."
+        
+        loader = OnlinePDFLoader(pdf_doc.name)
+        documents = loader.load()
+        loader = OnlinePDFLoader(pdf_doc.name)
+        documents = loader.load()
+        text_splitter = CharacterTextSplitter(chunk_size=1000, chunk_overlap=100)
+        texts = text_splitter.split_documents(documents)
+        embeddings = OpenAIEmbeddings()
+        global db
+        db = Chroma.from_documents(texts, embeddings)
+        retriever = db.as_retriever()
+        global qa 
+        qa = ConversationalRetrievalChain.from_llm(
+        llm=OpenAI(temperature=0.2, model_name="gpt-3.5-turbo-16k", max_tokens=-1, n=2),  
         retriever=retriever, 
         return_source_documents=False)
-    return "Ready"
+        return "Ready"
+    except Exception as e:
+        return f"Error loading PDF: {e}"
 
 def clear_data():
     global qa, db