[Minor] WebUI: Add comment for removeEventListener

Document that unconditional removeEventListener call is safe per MDN spec.

diff --git a/interface/js/main.js b/interface/js/main.js
index b2a3b37f19d28d43613f9d59f8acee24999cb888..85e06d8e2789ff9d9f4d4bf96d68f8741b937ed5 100644 (file)
--- a/interface/js/main.js
+++ b/interface/js/main.js
@@ -76,6 +76,7 @@
             apply(getEffectiveTheme(themePref));
 
             const {isAuto} = normalizeTheme(themePref);
+            // Safe to call even if listener isn't attached (MDN doc)
             mq.removeEventListener("change", handler);
             if (isAuto) {
                 mq.addEventListener("change", handler);