PF_precache_model_I: Bad string ' ' = Your string passed is wrong, more null string, that's why you better use copy(). Something you could check yourself if your var holds well the expected value before precaching.
Host_Error: no precache: models/blockmaker/bm_block_platform.mdl = Your call a native which needs such model and this one is not precached.
So, the problem is probably the model is not precached properly from the start.