prevent calling setGpu when the image selection is empty

[gautamkrishnar]

Calling setGpu when user hasnt seleted any images causes the wizzard to crash with the following error:

/wizard/index.js:79
  for (var i=0; i<imagesI.images.length; i++) {
                                 ^

TypeError: Cannot read properties of undefined (reading 'length')
    at setGpu (/wizard/index.js:79:34)
    at Socket.install (/wizard/index.js:115:23)
    at Socket.emit (node:events:517:28)
    at Socket.emitUntyped (/wizard/node_modules/socket.io/dist/typed-events.js:69:22)
    at /wizard/node_modules/socket.io/dist/socket.js:697:39
    at process.processTicksAndRejections (node:internal/process/task_queues:77:11)

Node.js v18.20.6

This occurs whenever user choses to use the GPU but skips selecting an image.

The fix

• Prevented calling setGpu when there are no images selected

[gautamkrishnar]

cc: @j-travis @thelamer