GetMass Correctly

I searched, found no answers.
I fiddled around with other addons, trying my own stuff
for about an hour, and I can’t figure it out.

When someone spawns a prop, I want to get the mass of that prop.
But nothing works.

[lua]
function GM:OnEntityCreated( prop )
if prop:GetClass() == “prop_physics” then

mass = prop:GetPhysicsObject():GetMass()
Msg(mass)

end end
[/lua]

I get this error:

[lua] [@gamemodes\ \gamemode\init.lua:???] Tried to use invalid object (type IPhysicsObject) (Object was NULL or not of the right type)(Hook: OnEntityCreated) [/lua]

You forgot an end and you are not doing anything with the mass variable.

I erased some of my unneeded code to post here (I also tested removing it in game, and I still get the error) Oh, and I know I forgot an end.

Untested:
[lua]
function GM:OnEntityCreated( prop )
if prop:GetClass() == “prop_physics” then
if prop:GetPhysicsObject():IsValid() then --check if the physics object is valid
phys = prop:GetPhysicsObject()
Msg(phys:GetMass() … "
")
end
end
end
[/lua]

-snip-

That worked, thunder. Except all props have the same mass. D:
[lua] function GM:OnEntityCreated( prop )
if prop:GetClass() == “prop_physics” then
if prop:GetPhysicsObject():IsValid() then
phys = prop:GetPhysicsObject()
Mass=phys:GetMass()
Msg(Mass)
end

prop:SetNWFloat(“PropHealth”,50+Mass )
end end
[/lua]

I have no idea what cold cause props having all the same mass try to do

prop:SetNWFloat(“PropHealth”, 50+phys:GetMass())