I can not load mods installed through twitch

I am installing mods using twitch but it is imposible to load them. In the launcher log you can read:  

: Couldn't load local version C:\Users\USUARIO\Twitch\Minecraft\Install\versions\1.14.4\1.14.4.json

Couldn't load local version C:\Users\USUARIO\Twitch\Minecraft\Install\versions\1.15-pre3\1.15-pre3.json

 

[19:22:10 FATAL]: Unhandled exception in thread Thread[AWT-EventQueue-0,6,main]

com.google.gson.JsonSyntaxException: duplicate key: null