Add default value for point_radius_fixed

[betodealmeida]

As the title says. I came across this bug when developing the time scrubber.

[mistercrunch]

I think it's fixed on the client side of things now here:
#4261

Should be impossible to return null at this point.

Can you check that this commit was not in your branch?

[betodealmeida]

You're right, this is now fixed and no longer needed.