error: input appears to be encoded with UTF-8, but found invalid byte
  --> testdata/encoding/utf8-invalid.proto:19:11
   |
19 | syntax = "<FF>";
   |           ^^^^
   = note: non-UTF-8 byte occurs at offset 701 (0x2bd)
   = note: Protobuf files must be UTF-8 encoded

encountered 1 error
