fixed issue when reloading the extension

Former-commit-id: d52527435cf70fe7ea647e8e1090dbae8e6158bc

extension/core/content/content-main.js

@@ -54,7 +54,7 @@ this.singlefile.extension.core.content.main = this.singlefile.extension.core.con
 	async function savePage(message) {
 		const options = message.options;
 		if (!processing) {
-			options.updatedResources = singlefile.extension.core.content.updatedResources;
+			options.updatedResources = singlefile.extension.core.content.updatedResources || {};
 			Object.keys(options.updatedResources).forEach(url => options.updatedResources[url].retrieved = false);
 			let selectionFound;
 			if (options.selected) {