inductiveUnivErrorMsg.lean:1:0-3:27: error: Resulting type is of the form
  Type ?u
but the universes of constructor arguments suggest that this could accidentally be a higher universe than necessary. Explicitly providing a resulting type will silence this error. Universe inference suggests using
  Type u_1
if the resulting universe level should be at the above universe level or higher.

Explanation: At this point in elaboration, universe level unification has committed to using a resulting universe level of the form `?u+1`. Constructor argument universe levels must be no greater than the resulting universe level, and this condition implies the following constraint(s):
  u_1 ≤ ?u+1
However, such constraint(s) usually indicate that the resulting universe level should have been in a different form. For example, if the resulting type is of the form `Sort (_ + 1)` and a constructor argument is in universe `Sort u`, then universe inference would yield `Sort (u + 1)`, but the resulting type `Sort (max 1 u)` would avoid being in a higher universe than necessary.
inductiveUnivErrorMsg.lean:5:0-7:29: error: Resulting type is of the form
  Type ?u
but the universes of constructor arguments suggest that this could accidentally be a higher universe than necessary. Explicitly providing a resulting type will silence this error. Universe inference suggests using
  Type u_1
if the resulting universe level should be at the above universe level or higher.

Explanation: At this point in elaboration, universe level unification has committed to using a resulting universe level of the form `?u+1`. Constructor argument universe levels must be no greater than the resulting universe level, and this condition implies the following constraint(s):
  u_1 ≤ ?u+1
However, such constraint(s) usually indicate that the resulting universe level should have been in a different form. For example, if the resulting type is of the form `Sort (_ + 1)` and a constructor argument is in universe `Sort u`, then universe inference would yield `Sort (u + 1)`, but the resulting type `Sort (max 1 u)` would avoid being in a higher universe than necessary.