[PartialCloning]

#include <amxmodx>
#include <engine>
#include <fakemeta>
#include <webserver>

public plugin_init()
{
    WS_RegisterRequestCallback("home", "OnWebServerHome");
    WS_RegisterRequestCallback("motd", "OnWebServerHome");
}

public OnWebServerHome(WSConnection:Connection, const Method[], const URL[])
{
    static ThresHold;
    server_print("%d", ThresHold++);

    return MHD_NO;
}

public server_frame()
{
    static i, Index, Body, Classname[64];
    for(i = 1; i <= MaxClients; i++)
    {
        if(!is_user_connected(i))
            continue;

        get_user_aiming(i, Index, Body, 6000);
        pev(Index, pev_classname, Classname, charsmax(Classname));
        server_print("Classname: %s.", Classname);
    }
}

Use that, the server should crash not long after you hold refresh.

Edit: I tried it on a listen server and it does crash the game. Nothing else running other than the amxmodx main plugins.