roblox_emulator: support more Vector3.new argument variants

lib/roblox_emulator/src/runner/vector3.rs

@@ -16,8 +16,12 @@ pub fn set_globals(lua:&mlua::Lua,globals:&mlua::Table)->Result<(),mlua::Error>{
 
 	//Vector3.new
 	table.raw_set("new",
-		lua.create_function(|_,(x,y,z):(Number,Number,Number)|
-			Ok(Vector3::new(x.into(),y.into(),z.into()))
+		lua.create_function(|_,(x,y,z):(Option<Number>,Option<Number>,Option<Number>)|
+			match (x,y,z){
+				(Some(x),Some(y),Some(z))=>Ok(Vector3::new(x.into(),y.into(),z.into())),
+				(None,None,None)=>Ok(Vector3(glam::Vec3A::ZERO)),
+				_=>Err(mlua::Error::runtime("Unsupported arguments to Vector3.new")),
+			}
 		)?
 	)?;