fix: fallback to default cron period when setting is not yet initialized

On fresh activation, getSetting() returns a non-string value before
settings are saved, triggering a warning. Fall back to 'ntfn_week'
(the registered default) instead of erroring.

Author: jakubmikita

readme.txt

@@ -297,6 +297,9 @@ Yes! We're offering a [custom plugin development](https://bracketspace.com/custo
 
 == Changelog ==
 
+= [Next] =
+* [Fixed] Warning on activation when cron period setting is not yet initialized
+
 = 9.0.9 =
 * [Fixed] Plugin crash on certain hosting configurations due to missing build file
 

src/Core/Cron.php

@@ -72,8 +72,7 @@ public function registerCheckUpdatesEvent()
 		$schedule = \Notification::settings()->getSetting('triggers/wordpress/updates_cron_period');
 
 		if (! is_string($schedule)) {
-			ErrorHandler::error('Update cron period is not a string');
-			return;
+			$schedule = 'ntfn_week';
 		}
 
 		if ($event === false) {