Two collapsed line continuations, and a branch that could not fire

The extern-boundary refusal and a restart-case one each had a run of spaces
mid-sentence where an OCaml line continuation had been lost. The textures lane
found the first while reading the FFI rules; the second was mine, from the same
editing mistake in the same week.

The restart-case one turned out to be unreachable as well. Each clause is
checked with the type the form has already settled on, so a clause that
disagrees is refused by expect where it is written - the dedicated message
could only have fired if that check did not, and it does. Removed rather than
reworded; a message nothing can produce is worse than no message, because the
next person tries to work out what reaches it.

.gitignore

@@ -42,3 +42,4 @@ old-ocaml/
 /calc-me
 /sand
 /conditions-play
+.claude/

lib/check.ml

@@ -652,16 +652,11 @@ and check_restart_case ctx ?want loc body clauses =
          if List.mem c.Ast.rname !seen then
            fail c.Ast.rloc "this restart-case offers %s twice" c.Ast.rname;
          seen := c.Ast.rname :: !seen;
+         (* Each is checked against what the form has settled on so far, so a
+            clause that disagrees fails where it is written. The first one to
+            produce a value is what settles it when nothing outside did. *)
          let b = block ctx ?want:!ty c.Ast.rloc c.Ast.rbody in
-         if b.Tast.ty <> Types.Never then begin
+         if !ty = None && b.Tast.ty <> Types.Never then ty := Some b.Tast.ty;
-           match !ty with
-           | None -> ty := Some b.Tast.ty
-           | Some t when not (Types.fits ~expected:t ~actual:b.Tast.ty) ->
-             fail c.Ast.rloc
-               "the %s clause has type %s but this restart-case has type %s —                 every clause and the body must agree, since the form yields                 whichever of them ran"
-               c.Ast.rname (Types.to_string b.Tast.ty) (Types.to_string t)
-           | Some _ -> ()
-         end;
          { Tast.rname_id = type_id c.Ast.rname; rname = c.Ast.rname;
            rbody = [ b ] })
       clauses
@@ -1338,7 +1333,8 @@ let collect env (decls : Ast.decl list) =
            | Types.String | Types.Slice _ when what = "a parameter" -> ()
            | _ ->
              fail loc
-               "%s of %s is %s, which cannot cross to C directly — pass                 (Ptr %s) and let the shim read it" what fn.Ast.name
+               "%s of %s is %s, which cannot cross to C directly — pass \
+                (Ptr %s) and let the shim read it" what fn.Ast.name
                (Types.to_string t) (Types.to_string t)
          in
          List.iter (crossable "a parameter") params;