Adam was already mortal

Genesis 3:22

(22) And the LORD God said, Behold, the man is become as one of us, to know good and evil: and now, lest he put forth his hand, and take also of the tree of life, and eat, and live for ever: (23) Therefore the LORD God sent him forth from the garden of Eden, to till the ground from whence he was taken.

Had they eaten the fruit of the second tree, then they would live forever, they were already mortal.

Genesis 2:15

But of the tree of the knowledge of good and evil, thou shalt not eat of it: for in the day that thou eatest thereof thou shalt surely die.

A bit weird to get mad at someone for doing something bad/evil, when they literally didn't know what good and evil was and thus wouldn't know that disobeying god was a bad thing.
And also strange that god lied here, seeing as they ate the fruit and didn't die (yeah yeah "spiritual death", why wouldn't god just say that if that's what he meant)