Prep Plugin for release on WordPress.org

Escape everything that should be escaped.
Add nonce checks where needed.
Sanitize all inputs.
Apply Code style changes across the codebase.
Correct many deprecation notices.
Optimize load order of many filters.

inc/functions/date.php

@@ -74,9 +74,9 @@ function wu_get_days_ago($date_1, $date_2 = false) {
 
 	$datetime_2 = wu_date($date_2);
 
-	$dateIntervar = $datetime_1->diff($datetime_2, false);
+	$date_intervar = $datetime_1->diff($datetime_2, false);
 
-	return - $dateIntervar->days;
+	return - $date_intervar->days;
 }
 
 /**
@@ -90,7 +90,7 @@ function wu_get_current_time($type = 'mysql', $gmt = false) {
 
 	switch_to_blog(wu_get_main_site_id());
 
-		$time = current_time($type, $gmt); // phpcs:ignore
+	$time = current_time($type, $gmt); // phpcs:ignore
 
 	restore_current_blog();
 
@@ -121,7 +121,6 @@ function wu_filter_duration_unit($unit, $length) {
 			$new_unit = $length > 1 ? __('Years', 'wp-multisite-waas') : __('Year', 'wp-multisite-waas');
 			break;
 		default:
-			$new_unit = $new_unit;
 			break;
 	}
 
@@ -181,10 +180,10 @@ function wu_convert_php_date_format_to_moment_js_format($php_date_format): strin
 		'g' => 'h',
 		'H' => 'HH',
 		'h' => 'hh',
-		'I' => '',       // Daylight Saving Time? => moment().isDST();
+		'I' => '',       // Daylight Saving Time?: moment().isDST().
 		'i' => 'mm',
 		'j' => 'D',
-		'L' => '',       // Leap year? => moment().isLeapYear();
+		'L' => '',       // Is Leap year?: moment().isLeapYear().
 		'l' => 'dddd',
 		'M' => 'MMM',
 		'm' => 'MM',