The error message is relatively clear, there is an unknown character in /Users/nathan/nathom.github.io/assets/js/solve2048/pkg/solve2048_bg.wasm. If you use VSCode there is a plugin that can help displaying special characters. Without knowing what is in your wasm file this is a black box.
js.Build is using esbuild under the hood though, and it looks like it needs a bit more to understand wasm. Maybe build that script outside of Hugo and then use the result in your pipeline?