Fixes error when not finding any tweets

app.py

@@ -43,7 +43,7 @@ app_ui = ui.page_navbar(
         ),
         align="right",
     ),
-    selected="search_engine",
+    selected="intro",
     fluid=False,
     title=ui.div(ui.img(src="favicon.ico", width="75dpi", height="75dpi"),
                  ui.h1("Copbird")),

src/mod_searchable.py

@@ -58,7 +58,7 @@ def search_query(query: str, limit: int = 5, sorting_method: str = "score") -> (
     result = tweets.iloc[correct_indices]
 
     if not len(result):
-        return None
+        return None, 0
 
     if limit == -1:
         limit = len(result)