I was in the middle of a game when all of a sudden the game closes

when I reopened the game i got this error

java.util.ConcurrentModificationException

at java.util.HashMap.forEach(HashMap.java:1283)

at ekd.close(SourceFile:163)

at djz.close(SourceFile:978)

at djz.l(SourceFile:957)

at net.minecraft.client.main.Main.main(SourceFile:229)

please hep