Am I correct in assuming that you can't roll the bonus die for spending salvage if you don't have any scientists on the reasearch? I couldn't find this clarified anywhere in the app, and if you can roll without a scientist there is no risk.

I found in another thread that the answer is under Tasks/Rolling dice and that you can't add to a dice pool of 0.

It's totally covered by the rules.

Under "Tasks/Rolling Dice"

A player cannot roll an additional die if he or she is not already rolling at least one die.