Make CrashReporterStartOptions.extra have only string properties

github-electron/github-electron-main-tests.ts

@@ -497,7 +497,10 @@ crashReporter.start({
 	productName: 'YourName',
 	companyName: 'YourCompany',
 	submitURL: 'https://your-domain.com/url-to-submit',
-	autoSubmit: true
+	autoSubmit: true,
+	extra: {
+		someKey: "value"
+	}
 });
 
 // nativeImage

github-electron/github-electron.d.ts

@@ -1353,7 +1353,7 @@ declare module GitHubElectron {
 		* Only string properties are send correctly.
 		* Nested objects are not supported.
 		*/
-		extra?: any;
+		extra?: {[prop: string]: string};
 	}
 
 	interface CrashReporterPayload extends Object {