I also had the same problem with zombie kids. I was getting attacked by a zombie kid through 1 block of cobblestone, 2 cobblestone blocks prevents the hit. 1 cobblestone block should be sufficient however.
@andzej I've already done that. The launcher works, but there are times when it won't work. And the times it won't work are random. The reason it randomly doesn't work is because the Native launcher updater runs itself when I try to run Minecraft, gives me the error code 5, and I have to copy over the .tmp file I renamed to the Minecraft folder I created, per instructions relating to MCL-5291.
I am having the same problem, and have created an issue. Hasn't been looked at yet, but the issue number is MC-234547 Game crashed, Exit Code: 0.
After clicking on play 2 times and getting the error for no reason, clicking play a 3rd time finally let the game run normally.