How to prevent tsdx outputting multiple chunks?

[MagnusBrzenk]

I am building a library that depends on three.js v128. Rather than making the users add the three.js dependency themselves, I sought to conditionally add it within the UMD script. However, in order for this to work, I have to first load three.js and only then run the library. I therefore tried to do the following:

      // ... code to conditionally load three.js v128
      import('./path/to/my/three.js/stuff').then(ThreejsScene => {
        threejsScene = new ThreejsScene.ThreejsScene();
        threejsScene.init();
      });

... this works in development environment BUT when I try to build a UMD it gives me an error due to wanting to output multiple chunks. But I don't want multiple chunks -- I want to keep a single file UMD, the only reason for the relative import being that I need to first ensure that three.js v128 is loaded and only then load stuff that depends on there being a gloabl variable THREE.

Is what am I trying to do possible?