C/C++ and JS hybrid project results in invalid file extension for js output
So, I was coding a site, and figured if nim can compile to JS, I can just write everything in Nim, and i decided to make a peculiar monolith project structure for backend in C/C++ and Frontend code in JS:

```
project
│  config.nims
│  site.nimble
├──build
│  │  site.exe
│  └──js
│       test.exe
└──src
   │  site.nim
   │  router.nim
   └──js
        config.nims
        test.nim
```
Where `/src/js/config.nims` contains `setCommand("js")`. I added `js/test` to `site.nimble` bin and run command:
```sh
nimble build
```
JavaScript output compiles just fine, HOWEVER, as you can probably see, the extension for `build/js/test` is EXE. Yes, an EXE file with javascript inside.

This is somewhat troublesome... Don't know if its a bug or a feature, of if I'm just doing something stupid. Is there any way to stop nimble from naming js output as `.exe`?