Why does Solution Checker not recognize "use strict" in the beginning of a Javascript Webresource?

The new Solution Checker of Dynamics Admin Area has some really nice features to validate Customizations.

https://docs.microsoft.com/en-us/powerapps/maker/common-data-service/use-powerapps-checker

But I am struggling with keeping my Javascript Files "clean".

The following script in a Script Webresource validates OK

function mySolutionCheckerFunction() {"use strict";
var number = 1+1;

}

But why does the following code not pass the Solution Checker?

"use strict";

function mySolutionCheckerFunction() {

var number = 1+1;

}