fixed progress bar issue

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

@@ -185,7 +185,6 @@ this.SingleFileCore = this.SingleFileCore || (() => {
 			let indexResource = 0;
 			return Promise.all(resourceURLs.map(async resourceURL => {
 				const resourceRequests = this.requests.get(resourceURL);
-				indexResource = indexResource + 1;
 				try {
 					const dataURI = await Download.getContent(resourceURL, { asDataURI: true, maxResourceSize: options.maxResourceSize, maxResourceSizeEnabled: options.maxResourceSizeEnabled });
 					resourceRequests.forEach(resourceRequest => resourceRequest.resolve(dataURI));
@@ -193,6 +192,7 @@ this.SingleFileCore = this.SingleFileCore || (() => {
 					resourceRequests.forEach(resourceRequest => resourceRequest.reject(error));
 				}
 				this.requests.delete(resourceURL);
+				indexResource = indexResource + 1;
 				onloadListener({ index: indexResource, max: resourceURLs.length, url: resourceURL });
 			}));
 		}