The web has no built-in file listing feature. You can only make HTTP requests to named resources. Construct knows which files are in your project, but it doesn't know if you uploaded any other resources after exporting your project, so it can't have a true "list files" features.
It should be easy to work around though: either keep your own array of filenames somewhere, or what I'd recommend is having a top-level import for the folder. For example if you have the files:
myfolder/module1.js
myfolder/module2.js
myfolder/module3.js
Then add myfolder/main.js which imports those modules. You can use "export from" syntax to conveniently re-export everything without having to list all its exports, e.g.:
export * from "./module1.js";
export * from "./module2.js";
export * from "./module3.js";
Then if you import myfolder/main.js you get all the modules in that folder imported. If you need to add a new file, then you can add module4.js in "myfolder", and then add a new line in main.js to export it too.