Fix NULL error

[Astralcircle]

Fixes:

lua/webaudio/receiver.lua:335: Tried to use a NULL entity!
    1. WorldToLocal - [C]:-1
        2. updateObject - lua/webaudio/receiver.lua:335
            3. func - lua/webaudio/receiver.lua:385
                4. unknown - lua/includes/extensions/net.lua:38

[Vurv78]

I never did this because it was never reproducable and couldn't think of why it'd happen.
Adding an IsValid there just feels like a hack.

#42 (comment)
#60

But ig I'll merge later on if you don't have anything to reproduce the issue.

[Astralcircle]

An entity may become invalid while it is being transmitted to the network.

[Vurv78]

Yes, that's what you'd think. I don't remember fully since it's been so long but I'm pretty sure I'd have tested the case for that and still not have been able to reproduce it.

Something like this:

@inputs P:entity # ensure wired
const Wa = webAudio(...)
Wa:setParent(P)
Wa:transmit()
P:propDelete()