phpstan: refactor code to be more clear

* remove unneccessary null/isset checks

* catch rule object creation exceptions

* checks for 'false' return of wp_json_encode

* logs to error when WP_DEBUG

* return '' // graceful return in admin settings page (as stated in docstring)

src/Service/BookingRuleApplied.php

@@ -8,6 +8,7 @@
 use CommonsBooking\Repository\UserRepository;
 use CommonsBooking\Settings\Settings;
 use CommonsBooking\Wordpress\Options\OptionsTab;
+use Exception;
 
 /**
  * Represents a valid configuration of a {@see BookingRule}, which can be applied to bookings.
@@ -187,24 +188,26 @@ public static function bookingConformsToRules( Booking $booking):void {
 	}
 
 	/**
-	 * Gets a string of all rule properties, so they can be displayed using CMB2
+	 * Retrieves a JSON string of all rule properties to display using CMB2.
 	 *
-	 * Will ignore errors, so that the settings page can still display the selected values even if they are invalid
-	 * @return string
+	 * If initialization or encoding fails, returns an empty string to ensure the page functions.
+	 *
+	 * @return string JSON-encoded rule properties, or an empty string on failure.
 	 */
 	public static function getRulesJSON(): string {
-		$ruleObjects = static::init( true );
-
-		if ( isset( $ruleObjects ) ) {
-			return wp_json_encode(
-				array_map(
-					function( $rule){
-						return get_object_vars($rule);
-					}, $ruleObjects )
-			);
-		}
-		else {
-			return "";
+		try {
+			$ruleObjects = static::init(true);
+
+			// Ensure we return valid JSON or an empty string if encoding fails
+			return wp_json_encode(array_map(function($rule) {
+				return get_object_vars($rule);
+			}, $ruleObjects)) ?: '';
+		} catch (Exception $e) {
+			if (WP_DEBUG) {
+				error_log( $e->getMessage() );
+			}
+
+			return ''; // Return an empty string if initialization or encoding fails
 		}
 	}