bug?: showSaveFilePicker does not works in firefox

[原劍]

import { showDirectoryPicker, showOpenFilePicker, showSaveFilePicker } from 'native-file-system-adapter';

showDirectoryPicker and showOpenFilePicker work in firefox.

but showSaveFilePicker does not work in firefox. it cannot show the popup dialogue.

it works with chromium, opera etc.

saveFile: async() => {
	const fileHandle = await showSaveFilePicker({
		_preferPolyfill: false,
		suggestedName: 'Untitled',
		excludeAcceptAllOption: false // default
		});
		console.log(fileHandle);  //it could print to console.
	}

test env: ionic + vue