Swedish intervention during the invasion of Norway

What if Sweden went to war with Germany when Norway was invaded?

German forces would face a costly cold-weather and guerrilla campaign while Norwegian troops gained a friendly refuge and source of support.

Swedish entry would give Norwegian troops somewhere to withdraw, recover, and continue fighting rather than leaving them isolated. Swedish support could sustain a guerrilla campaign in terrain where German mobility and air power offered no quick solution. Germany had already suffered important naval and operational losses during the invasion. Opening another cold-weather front against Sweden would turn Norway into a prolonged and expensive commitment.