Napoleonic Wars, WW1, WW2. Not even including the US, Russia, China and Japan all had explosive growth after WW2.
War is a net negative every time.
If a sudden drop in working age labor causes a death spiral, then Russia would have had a death spiral after WW2. Instead they had a boom and put a man in space before the US.
The labor involved with raising children is similar but is closer to an investment.
It's not an investment because at the end of a child's growth, you now have a consumer who requires more resources. When an elderly dies, that frees up resources for everyone.
The Black Plague is a accepted factor for the Renaissance. Labor became more valuable. The death of so many workers allowed the surviving workers wages to increase and they got more independence. It wasn't a death spiral.
BUT you do have less total labor.
Total less labor isn't a problem when you don't need more labor.
If you shrink your labor pool too quickly, you won’t be able to sustain your infrastructure causing a collapse.
WW2 was a far quicker and far more severe labor pool shrinkage for many countries in the world. There was no collapse.