function GetApp( appid, callback )
{
	if( nextAllowedRequest > 0 && Date.now() < nextAllowedRequest )
	{
		callback( { success: false, error: 'Rate limited' } );
		return;
	}

	const params = new URLSearchParams();
	params.set( 'appid', Number.parseInt( appid, 10 ).toString() );

	fetch( `https://extension.steamdb.info/api/ExtensionApp/?${params.toString()}`, {
		headers: {
			Accept: 'application/json',
			'X-Requested-With': 'SteamDB',
		},
	} )
		.then( GetJsonWithStatusCheck )
		.then( callback )
		.catch( ( error ) => callback( { success: false, error: error.message } ) );
}
@param {string} appid
@param {(obj: {success: true}|{success: false, error: string}) => void} callback