Just a note to people running into the same problem as I did:

Problem: after installing the geo-ip and the OSM plugin into Mibew, nothing happens after clicking the IP of a user. There are no error messages inside the webserver's error.log and no javascript errors in the browser.

Solution: check manually if the GeoIP2 library works, e.g. by running a small test script from the plugins/Mibew/Mibew/Plugin/GeoIp directory:

<?php
require_once("vendor/autoload.php");
use GeoIp2\Database\Reader as GeoIpReader;
$reader = new GeoIpReader("db/GeoIP.mmdb");

In my case, I got the error:

PHP Fatal error: Uncaught RuntimeException: The gmp or bcmath extension must be installed to read this database. in /var/www/html/mibew/plugins/Mibew/Mibew/Plugin/GeoIp/vendor/maxmind-db/reader/src/MaxMind/Db/Reader/Decoder.php:259

After installing php-bcmath, everything worked as expected. Maybe this could be mentioned in the README or some other place.

BIG SHIT !
Just loosing your time with this!

Can we add IPv6 support?

Error on installing plugin! State says "not initialized"
That is not my problem but problem of thousand of users.
Just search around for phrase "Mibew not initialized".
And replies for it is like reply from 15years old's.

OS: Ubuntu 16.04 LTS, Mibew 3.2.1 GeoIP 1.0.2
Environment: PHP 7.0.32-0ubuntu0.16.04.1 PDO/7.0.32-0ubuntu0.16.04.1 pdo_mysql/7.0.32-0ubuntu0.16.04.1 gd/7.0.32-0ubuntu0.16.04.1 curl/7.0.32-0ubuntu0.16.04.1 mbstring/7.0.32-0ubuntu0.16.04.1

On installing the plugin, /index.php/operator/plugin produces the following error:
PHP message: PHP Warning: Application stopped because of uncaught exception vierbergenlars\SemVer\SemVerException "Invalid Version: 7.0.32-0ubuntu0.16.04.1 [[7.0.32-0ubuntu0.16.04.1]]

pluging state ERROR: "Not initialized".