Mid-game reporting

i recently was playing a game with one of the most toxic players i've met so far. i played with her for 3 games, trying to give her a chance. she never accepts responsibility for her actions and blames it on others, ranting in-game, verbally abusing the player that is lacking in the slightest. she attacked me for so long in the last game that i decided the leaverbuster penalty was far more worth it than to sit there and take the abuse she was pouring out. i would like an in-game option to report chat, since i will not have the option to report her after i leave... leaving the game is an irritating thing, yes, but being so toxic that you cause others is just as bad. i am simply asking for the ability to give proof that i had good reason to leave the game before leaverbuster starts piling on penalties. thank you for your consideration.