Fix unused var and pseudorandom warnings

src/scripts/datetime.js

@@ -211,7 +211,7 @@ export function getDisplayDateTime(date) {
     if (typeof date === 'string') {
         try {
             date = parseISO8601Date(date, true);
-        } catch (err) {
+        } catch {
             return date;
         }
     }
@@ -227,7 +227,7 @@ export function getDisplayTime(date) {
     if (typeof date === 'string') {
         try {
             date = parseISO8601Date(date, true);
-        } catch (err) {
+        } catch {
             return date;
         }
     }

src/scripts/keyboardNavigation.js

@@ -64,7 +64,7 @@ let hasFieldKey = false;
 try {
     hasFieldKey = 'key' in new KeyboardEvent('keydown');
 } catch (e) {
-    console.error("error checking 'key' field");
+    console.error("error checking 'key' field", e);
 }
 
 if (!hasFieldKey) {

src/scripts/screensavermanager.js

@@ -31,7 +31,7 @@ function getScreensaverPlugin(isLoggedIn) {
     let option;
     try {
         option = userSettings.get('screensaver', false);
-    } catch (err) {
+    } catch {
         option = isLoggedIn ? 'backdropscreensaver' : 'logoscreensaver';
     }