Implement automatic error logging for non-successful output.

[fogfish]

	return µ.GET(
		µ.URI(µ.Path("catalog"), µ.Path(lAuthorID), µ.Path("posts"), µ.PathAll(lObjectID)),
		µ.FMap(func(ctx *µ.Context, req *req) error {
			story, err := api.r.Story(ctx,
				core.NewStoryID(profile, string(req.objectID)),
			)
			if err != nil {
				// slog <-- looks redundant here.
				slog.Error("failed to fetch post", "err", err, "uri", ctx.Request.URL)
				return ø.Status.InternalServerError(
					ø.Error(err, "failed to fetch post"),
				)
			}
       ...

Embed slog within InternalServerError, each output needs to accept ctx.