Prevent resetting shipping providers after additional load call.

src/ShippingProvider/Helper.php

@@ -167,8 +167,6 @@ public function load_shipping_providers() {
 			return array();
 		}
 
-		$this->shipping_providers = array();
-
 		$shipping_providers   = WC_Data_Store::load( 'shipping-provider' )->get_shipping_providers();
 		$registered_providers = $this->get_shipping_provider_class_names();
 
@@ -181,10 +179,8 @@ public function load_shipping_providers() {
 		// For the settings in the backend, and for non-shipping zone methods, we still need to load any registered classes here.
 		foreach ( $shipping_providers as $provider_name => $provider_class ) {
 			if ( $cache = \Vendidero\Germanized\Shipments\Caches\Helper::get_cache_object( 'shipping-providers' ) ) {
-				$provider = $cache->get( $provider_name );
-
-				if ( ! is_null( $provider ) ) {
-					return $provider;
+				if ( $cache->get( $provider_name ) ) {
+					continue;
 				}
 			}