error: input appears to be encoded with UTF-8, but found invalid byte
  --> testdata/encoding/utf8-invalid.proto:5:11
   |
 5 | syntax = "<FF>";
   |           ^^^^
   = note: non-UTF-8 byte occurs at offset 95 (0x5f)
   = note: Protobuf files must be UTF-8 encoded

encountered 1 error
