If you create a custom activity more than once an exception should be thrown

1. Create new project
2. Try to extend the com.tns.NativeScriptActivity, which is create by tns-core-modules
   Code:

var MyCustomActivityClass = (function (_super) {
    __extends(MyCustomActivityClass, _super);
    function MyCustomActivityClass() {
        _super.call(this);
        return global.__native(this);
    }
    MyCustomActivityClass.prototype.onCreate = function (savedInstanceState) {
     	_super.prototype.onCreate.call(this, false ? savedInstanceState : null);
     	android.util.Log.d("Sbg.Test","we got called from onCreate of custom-activity.js");
    };

    MyCustomActivityClass = __decorate([
        JavaProxy("com.tns.NativeScriptActivity")
    ], MyCustomActivityClass);

    return MyCustomActivityClass;
}(android.app.Activity));

3. Build the app for android tns build android
   Actual: A warning will be logged "Warning: there already is an extend called com.tns.NativeScriptActivity."
   Expected: An exception to be thrown https://github.com/NativeScript/android-runtime/blob/2ab7271d12d56a03e57880a2b1783b08206363ae/test-app/build-tools/static-binding-generator/src/main/java/org/nativescript/staticbindinggenerator/Generator.java#L82

P.S. In some cases the exception is thrown, but this situations are very rare.

Start at the linked Generator.java location around line 82 and trace how duplicate extends for com.tns.NativeScriptActivity are handled. Run the reported custom-activity reproduction with tns build android; done means the duplicate extension produces the expected exception rather than only logging a warning.