Generic error if FS.createPreloadedFile parent doesn't exist

**Version of emscripten/emsdk:**
```
emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 3.1.59 (0e4c5994eb5b8defd38367a416d0703fd506ad81)
clang version 19.0.0git (https:/github.com/llvm/llvm-project df762a1643bb5b0b3c907611d118c82d4b68a39d)
```

I'm trying to preload some files (in a pre-js file):

```
Module.preRun = () => {
FS.createPreloadedFile('/data', 'journey-r83-s890706.z6', 'journey-r83-s890706.z6', true, false)
FS.createPreloadedFile('/data', 'Journey.blb', 'Journey.blb', true, false)
}
```

Since I forgot to create the `/data` folder first I'm getting a console errors, but they're very generic and unhelpful. Enabling `-sASSERTIONS` doesn't make a difference.

```
sfrotz.js:3406 Uncaught
sfrotz.html:195 [post-exception status] Exception thrown, see JavaScript console
sfrotz.js:3406 Uncaught
```