Fix failing config check when es6 notation is used

CHANGELOG.md

@@ -40,6 +40,7 @@ Special thanks to the following contributors: @B1gG, @codac, @ezeholz, @khassel,
 - Fix alert not recognizing multiple alerts (#2522)
 - Fix fetch option httpsAgent to agent in calendar module (#466)
 - Fix module updatenotification which did not work for repos with many refs (#1907)
+- Fix config check failing when encountering let syntax ("Parsing error: Unexpected token config")
 
 ## [2.15.0] - 2021-04-01
 

js/check_config.js

@@ -52,7 +52,13 @@ function checkConfigFile() {
 	// I'm not sure if all ever is utf-8
 	const configFile = fs.readFileSync(configFileName, "utf-8");
 
-	const errors = linter.verify(configFile);
+	// Explicitly tell linter that he might encounter es6 syntax ("let config = {...}")
+	const errors = linter.verify(configFile, {
+		env: {
+			es6: true
+		}
+	});
+
 	if (errors.length === 0) {
 		Log.info(Utils.colors.pass("Your configuration file doesn't contain syntax errors :)"));
 	} else {