Fix query parameter separator in API fetch URLs

Author: ajaydsouza

includes/admin/js/classic-sections-metabox.js

@@ -341,7 +341,8 @@
 		inflightKey = key;
 		renderSections([]);
 
-		apiFetch({ url: `${config.endpoint}?products=${encodeURIComponent(key)}` })
+		const separator = config.endpoint.indexOf('?') !== -1 ? '&' : '?';
+		apiFetch({ url: `${config.endpoint}${separator}products=${encodeURIComponent(key)}` })
 			.then((terms) => {
 				if (inflightKey !== key) {
 					return;

includes/admin/js/classic-sections-metabox.min.js

@@ -135,8 +135,9 @@ let wzkbSectionsNonceMiddlewareAdded = false;
             }));
 
             const query = encodeURIComponent(productKey);
+            const separator = config.endpoint.indexOf('?') !== -1 ? '&' : '?';
 
-            apiFetch({ url: config.endpoint + '?products=' + query })
+            apiFetch({ url: config.endpoint + separator + 'products=' + query })
                 .then((terms) => {
                     if (isCancelled) {
                         return;