The chain will be one link longer than necessary. How can I remedy the situation?
You don't. That situation is remedied by the device known as the "tension wheel": the bottom one of the two small cogs in the derailleur. Under spring action emanating from the joints between the derailleur parts (hanger-pivot and pivot-cage) the tension wheel picks up slack in the chain.
The tension wheel is necessary because various gear combinations generate various amounts of chain slack (relative to the most tense combination of largest ring to largest cog).
Given that your chain fits into the tightest combination (largest ring to largest cog), try shifting to the extreme opposite: smallest ring to smallest cog. You will see that the derailleur picks up this extreme amount of slack by the tension wheel swinging radically rearward. If the chain is not too loose in this situation, and isn't rubbing against itself anywhere (or coming close to doing so), then everything is cool.
The derailleur can pick up slack in excess of the minimum; a few extra links won't exceed its range. It's a good idea to have a few extra links in the chain, in case you have a road-side repair emergency that requires you to splice out and throw away a damaged link.