Creation of js/config.js / fixed. Fixes first time installation with 1.5.1

[mcm1957]

When installing 1.5.1 (= version without license check) at a system without any prio vis installation, the installation crashes when trying to read js&config.js at

ioBroker.vis/main.js

Line 160 in e87d80d

let data = await adapter.readFileAsync(adapterName, 'js/config.js');

as the file does not yet exist.

Version up to 1.4.16 create this file during license check as license data does not exist in the case of the first installation:
see

ioBroker.vis/main.js

Line 267 in 442157d

async function indicateError() {

Problem has been reported by issue #805

Solution implemented is to catch read error for non existing files.

Please check whether some other still needed information within js/config.js get lost due to removal of license checks.