Update extract_abs.py

extract_abs.py

@@ -307,6 +307,7 @@ def streamlit_extraction(search_term:Union[int,str], maxResults:int, filtering:s
     pmid_abs, sankey_initial = classify_abs.streamlit_getAbs(search_term_list, maxResults, filtering)
     if len(pmid_abs)==0:
         st.error('No results were gathered. Enter a new search term.')
+        return None, None, None
     else:
         found, relevant = sankey_initial
         epidemiologic = 0