Improve error handling for gadget goroutine failures

[dorser]

Summary

In internal/gadget/registry.go, gadgets run in goroutines and errors are only logged — there's no mechanism to surface failures back to the caller.

Current Code

go func(name string, config *GadgetConfig, gadgetCtx *gadgetcontext.GadgetContext) {
    if err := r.runtimeManager.RunGadget(gadgetCtx, config.Params); err != nil {
        slog.Error("Error running gadget", "name", name, "error", err)
    }
}(name, config, gadgetCtx)

Problems

1. If a gadget fails to start, the main process doesn't know
2. No way to trigger shutdown if a critical gadget fails
3. No health status reporting for running gadgets

What's Needed

Options:

• Return an error channel from RunAll that the caller can select on
• Use an errgroup.Group to manage goroutine lifecycle
• Add a callback/hook mechanism for gadget lifecycle events
• At minimum, propagate first error and cancel context

Files

• internal/gadget/registry.go
• cmd/micromize/root.go (caller)