Known bug: Chroma Hills HD pack will crash Minecraft or not load at 128x resolution. Fix to Minecraft for memory-related issues pending. If possible, use 64x resolution.
Update: This issue has been addressed. Minecraft on Switch will only load 64x.
Related: If you purchased Chroma Hills HD on Switch and you have linked your Switch to Microsoft Xbox Live account, you will be able to download Chroma Hills HD on Windows 10 for 128x and 64x.