I've never seen one of these "logic in html-attributes" systems take error checking seriously. In stimulus they start to mention it in "Designing For Resilience" (though only for feature-checking), but in "Working With External Resources" where it uses calls network/IO bound calls they never mention how to handle errors or if the framework just leaves it up to you. Stimulus is also where you need to write your own js code, so I guess you could handle it yourself but in turbo when I skimmed the handbook I find no mentions of what/how to handle errors (or even what happens when turbo gets one), and when loading stuff over the network that is pretty much crucial.
From the turbo handbook: "An application visit always issues a network request. When the response arrives, Turbo Drive renders its HTML and completes the visit." Using the phrase "When the response arrives" begs the question of what happens if it doesn't arrive, or if it takes a minute for it to arrive, or if it arrives but with a faulty status code.