If the resourcepack folder contains an "issueful" resourcepack, the game can't start successfully, even the resourcepack is not loaded

I put a resourcepack (folder not zip) in the resourcepacks folder. The resourcepack contains "zh-cn.lang" and "zh-cn.json". Then it launch successfully, using English and can't use other languages.
But if I add the zh-cn language to pack.mcmeta, or add a wrong information (for example, "notlanguage":{"zh-cn":{...}}), the game can't run normally, and with crash-reports which don't mention resourcepacks. 18w01a, too.
After removing the resourcepack, or delete wrong things or thing about languages of pack.mcmeta, the game launchs successfuly, also using English and can't use other languages.