error: enum type must define at least one value
  --> testdata/tags/enum.proto:19:1
   |
19 | enum Empty {}
   | ^^^^^^^^^^^^^

error: first value of open enum must be zero
  --> testdata/tags/enum.proto:31:10
   |
31 |     Z3 = 1;
   |          ^
  ::: testdata/tags/enum.proto:15:11
   |
15 | edition = "2023";
   |           ------ this makes `buf.test.Open1` an open enum
   |
   = help: open enums must define a zero value, and it must be the first one

error: first value of open enum must be zero
  --> testdata/tags/enum.proto:36:10
   |
36 |     Z4 = 1;
   |          ^
  ::: testdata/tags/enum.proto:35:33
   |
35 |     option features.enum_type = OPEN;
   |                                 ----
   |                                  |
   |                                  this makes `buf.test.Open2` an open enum
   |
   = help: open enums must define a zero value, and it must be the first one

encountered 3 errors
