I'm really close to putting out a first beta. I still can't figure out this bug, I might post the .map to see if anyone can figure it out.
search sv_setbrushmodel: null using the search function, there are many results to be read. 
Hey MrFish, if you havan't figured your problem out alrady I think searching would be a good idea. It helped me when i got the same error.
The problem I had is that somehow a door entity was created but without the actual door brush included in the entity. Here is an example.
What it shouldn't look like:
// entity 3
{
"classname" "func_door"
"angle" "-1"
"speed" "30"
"wait" "5"
}
What it should look like:
// entity 3
{
"classname" "func_door"
"angle" "-1"
"speed" "30"
"wait" "5"
// brush 0
{
( 96 320 160 ) ( 96 224 160 ) ( 0 320 160 ) atcs/eq2_bmtl_03_blue 0 85.3333740234 0 0.125 0.375 0 0 0
( 96 320 160 ) ( 0 320 160 ) ( 96 320 0 ) atcs/eq2_bmtl_03_blue 0 0 0 0.125 0.625 0 0 0
( 32 320 160 ) ( 32 320 0 ) ( 32 224 160 ) atcs/eq2_bmtl_03_blue 170.6666259766 0 0 0.375 0.625 0 0 0
( 0 224 0 ) ( 96 224 0 ) ( 0 320 0 ) atcs/eq2_bmtl_03_blue 0 85.3333740234 0 0.125 0.375 0 0 0
( 0 224 0 ) ( 0 224 160 ) ( 96 224 0 ) atcs/eq2_bmtl_03_blue 0 0 0 0.125 0.625 0 0 0
( 0 224 0 ) ( 0 320 0 ) ( 0 224 160 ) atcs/eq2_bmtl_03_blue 170.6666259766 0 0 0.375 0.625 0 0 0
}
}
It also made a func_door text appear in the dead centre of the grid because it had no origin. If you have it it would be a bit of a giveaway.
Hope this helps.