Had an issue like this stemming from viewmodel hands for a survivor, took me a while to fix but hoooly it was not this bad. L4D2 spaghetti strikes again
never, in my entire life, have i ever seen a harder game to make the most basic mods for than left 4 dead 2 i dont know how valve managed to make every step of an already grueling process (authoring source models) so, SO much worse in every way, i've never seen a source game that literally breaks any viewmodel you decompile
Ngl. Im glad that even pros like you get technical problems such as these... I thought having gazillion experience in source sdk would make you immune and create whatever you want.
From what I've observed, it started crashes when the game didn't render your custom crowbar model when you drop a melee for a split second. Compare when you add a default crowbar mesh into your mdl it didn't crashed and renders the model.
27:10 I think is because how the Worldmodel physics interact with the floor. The Handsaw interacts with the floor in other way than the original Crowbar and that make the game physics to mismatch and crash.