[JS] Problem with checking if the file was selected in the dialog box

Dear forum,

Though I have done this many times before, today I encountered a strange problem.

I want to make sure that the user selects a file before the script continues:

main();

function main() {
     if (File.fs == "Macintosh") {
		var csvFile = File.openDialog("Select a CSV File", function (f) { return (f instanceof Folder) || f.name.match(/\.csv$/i);} );  
     } else {  
		var csvFile = File.openDialog("Select a CSV File","CSV files:*.csv;All files:*.*");  
     }  

	if (cvsFile != null) {
		// do something
	}
}

The file has been selected and its properties are visible in the data browser, but the script throws an error: the file is undefined.

This happens on Windows 10, both in ESTK and VSCode: in InDesign 2023 and 2024, Bridge 2024, ESTK.

Any ideas?

— Kasyan