Delete your downloaded models and sprites and rejoin the game (if you get booted with "Model has changes since starting the game and check hardware" kind of error, you deleted models, while it was running, don't do that.

When you join it'll pull fresh copies.
for me, these were in:
Code: Select all
C:\Program Files (x86)\Steam\steamapps\common\Half-Life\cstrike_downloads\models\warcraft3
C:\Program Files (x86)\Steam\steamapps\common\Half-Life\cstrike_downloads\sprites\warcraft3
If you still get client world is null, open console and paste it in a reply so I can look it it, it's possible other files could need to be redone as well for some people.