diff options
| -rw-r--r-- | toplevel/vernacentries.ml | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/toplevel/vernacentries.ml b/toplevel/vernacentries.ml index ebe1e4fbed..d4cacf68b7 100644 --- a/toplevel/vernacentries.ml +++ b/toplevel/vernacentries.ml @@ -1496,7 +1496,10 @@ let vernac_undoto n = let vernac_focus gln = let p = Proof_global.give_me_the_proof () in let n = match gln with None -> 1 | Some n -> n in - Proof.focus focus_command_cond () n p; print_subgoals () + if n = 0 then + Errors.error "Invalid goal number: 0. Goal numbering starts with 1." + else + Proof.focus focus_command_cond () n p; print_subgoals () (* Unfocuses one step in the focus stack. *) let vernac_unfocus () = |