Stack Traceback when running the example

[SuganthanBC]

Here is what I get when trying to run the give example in terminal with command "lua a.lua",

lua: /usr/local/lib/lua/5.4/tween.lua:344: dt must be a number
stack traceback:
	[C]: in function 'assert'
	/usr/local/lib/lua/5.4/tween.lua:344: in method 'update'
	...skaran/Documents/Development/LUA/a.lua:7: in main chunk
	[C]: in ?

[AllMesi]