Bug 1873158 - Fix Thunderbird linting errors noticed by newer linter versions. rs=lint DONTBUILD

Unnecessary return statement. (no-useless-return)

--HG--
extra : amend_source : 89ce9291bea8b68349392e24ae1ddfb80f90463b

mail/components/extensions/test/browser/browser_ext_menus_replace_menu_context.js

@@ -46,7 +46,6 @@ add_task(async function overrideContext_with_context() {
           "Expected successful executeScript"
         );
         browser.test.sendMessage("testTabAccessDone", "executeScript_ok");
-        return;
       } catch (e) {
         browser.test.assertEq(
           "Missing host permission for the tab",

mailnews/addrbook/prefs/content/pref-directory-add.js

@@ -429,7 +429,6 @@ function onAccept(event) {
 
       Services.prompt.alert(window, document.title, errorText);
       event.preventDefault();
-      return;
     }
   } catch (outer) {
     console.error(