It's been my experience that the GM needs to fix such a situation.
Way back in 2e days, our group was uncoordinated. Our last 2e campaign only had one "healer" at campaign start, a paladin who could heal 2 hit points per day. The GM gave us more healing potions than you would find in a video game, and it still wasn't enough. We only lasted one session.
My first campaign of d20 Modern (I was a player) didn't have a healer. The game was new to all of us and none of us knew about surgery. We literally ran into the problem where we couldn't do plot (such as rescuing someone) because we were half-dead, and adventuring while half-dead is a really bad idea. I learned my lesson and insisted on a surgeon every d20 Modern campaign.
A healer stopped being necessary around the time people latched on to the 3e/Pathfinder 1e Wand of Cure Light Wounds, or 4e healing surges, or 5e Hit Dice. The OP's scenario would still have a problem though, as Strange Aeons is a very low-level adventure (I think it starts at 1st-level) so you're not seeing a lot of treasure and you're not crafting any wands. (I played in that adventure, as a cleric in fact.)