tests(sqljs): added explicit error code to fail the process

gulpfile.ts

@@ -337,7 +337,8 @@ export class Gulpfile {
                 grep: !!args.grep ? new RegExp(args.grep) : undefined,
                 timeout: 15000
             }))
-            .pipe(istanbul.writeReports());
+            .pipe(istanbul.writeReports())
+            .on('error', process.exit.bind(process, 1));
     }
 
     /**