courts “ordinarily ... are not to assume the existence of jurisdiction in favor of reaching an ‘easier’ merits issue.” Bush, 304 F.3d at 193 (quoting Fidelity Partners, Inc. v. First Trust, Co. of N.Y., 142 F.3d 560, 565 (2d Cir.1998)). The only exception relevant here is “in those ‘particular circumstances’ where the ou