Add better handling for file URIs

Author: AA-Turner

templates/switchers.js

@@ -87,6 +87,7 @@ const _navigate_to_first_existing = (urls) => {
 
 const _on_version_switch = (event) => {
   if (_IS_LOCAL) return;
+
   const selected_version = event.target.value;
   // English has no language prefix.
   const new_prefix_en = `/${selected_version}/`;
@@ -111,6 +112,7 @@ const _on_version_switch = (event) => {
 
 const _on_language_switch = (event) => {
   if (_IS_LOCAL) return;
+
   const selected_language = event.target.value;
   // English has no language prefix.
   const new_prefix =