fix clear on empty

app/rag.py

@@ -107,8 +107,9 @@ class ChatPDF:
         return streaming_response
 
     def clear(self):
-        self.client.delete(collection_name="rag_documents", points_selector=self.doc_ids)
-        self.pdf_count = 0
-        self.text_chunks = []
-        self.doc_ids = []
-        self.nodes = []
+        if self.doc_ids:
+            self.client.delete(collection_name="rag_documents", points_selector=self.doc_ids)
+            self.pdf_count = 0
+            self.text_chunks = []
+            self.doc_ids = []
+            self.nodes = []