Not registering worker

Hello,
I have this plugin and OneSignal both installed and while the latter works, your plugin doesn’t.

In the console there’s this relevant error:
OneSignalSDKWorker.js.php:108 Uncaught SyntaxError: Cannot use import statement outside a module

And below it:
Registration failed with TypeError: Failed to register a ServiceWorker for scope (‘https://www.artedellalettura.it/’) with script (‘https://www.artedellalettura.it/OneSignalSDKWorker.js.php’): ServiceWorker script evaluation failed

How can I solve? Thanks

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