Add fake client check to CalculateMaxSpeed

[M60TM]

L 09/03/2023 - 19:55:19: [SM] Exception reported: Entity 22 (22) is invalid
L 09/03/2023 - 19:55:19: [SM] Blaming: tf2attribute_support.smx
L 09/03/2023 - 19:55:19: [SM] Call stack trace:
L 09/03/2023 - 19:55:19: [SM]   [0] GetEntPropEnt
L 09/03/2023 - 19:55:19: [SM]   [1] Line 587, C:\suspawn\mystuff_7040\scripting\tf2attribute_support.sp::OnPlayerCalculateMaxSpeedPost

This error also is occurred in SM 1.11. It seems to enough adding index check.

[nosoop]

22 should be within the MaxClients range, so I'd be surprised if your range check works there unless you have a really low player limit set.

[M60TM]

I got that error log on 33 max player server. It works, but I still don't know how that work. maybe I need more test.

[M60TM]

After test, I found some interesting points.

1. It is appeared when map change with "bot". (I don't know why it is appeared in server that doesn't have bots.)
2. IsValidEntity can't fix this problem.
3. client index check can't fix this problem.
4. I added IsFakeClient check, it fixed.

As a result, this error seems to be related with bots.

[M60TM]

I can't find a way to solve this. I'll try again later when I get a clearer clue.