Light's mistakes are part of the plot, not an error in it. He eventually loses as the Shinigami predicts that he will be the one writing his name on his Death Note. L also sacrifices himself knowing that he should close down on Kira and Near eventually puts an end to it. Yet my issue was with Light killing using the bag of chips with the TV inside, what kinda TV could fit there and render visible information with low light in a dark surveilled room?