fixed closure

lib/single-file/single-file-core.js

@@ -345,6 +345,7 @@ this.singlefile.lib.core = this.singlefile.lib.core || (() => {
 				const [resourceURL, asBinary] = JSON.parse(requestKey);
 				const resourceRequests = this.requests.get(requestKey);
 				try {
+					const currentIndexResource = indexResource;
 					indexResource = indexResource + 1;
 					const content = await util.getContent(resourceURL, {
 						asBinary,
@@ -357,7 +358,7 @@ this.singlefile.lib.core = this.singlefile.lib.core || (() => {
 						resourceRequests.forEach(callbacks => {
 							const duplicateCallbacks = this.duplicates.get(requestKey);
 							const duplicate = duplicateCallbacks && duplicateCallbacks.length > 1 && duplicateCallbacks.includes(callbacks);
-							callbacks.resolve({ content: content.data, indexResource: indexResource - 1, duplicate });
+							callbacks.resolve({ content: content.data, indexResource: currentIndexResource, duplicate });
 						});
 					}
 				} catch (error) {