Why does the following bar check fail for measure 3?

[Kevin Cole]

Hi,

In the following example lyrics, what goes wrong at measure 3?

Thanks!

%%%%
\version "2.20.0"
\language "english"

\header {
  title = "broken"
  tagline = ""
}

\layout {
  \autoBeamOff
}

global = {
  \key c \major
  \time 3/4
}

melody = {
  \relative {
    \global
    g'2 c8. a16       | %   1
    g4 e4 e8. d16     | %   2
    c2 r4             | %   3
    r4 r4 g'4         | %   4
  }
}

words = \lyricmode {
  This is ok         | %   1
  And so is this     | %   2
  ???                | %   3
  ok                 | %   4
}

\score {
  <<
    \new Staff { \melody }
    \addlyrics { \words }
  >>
}
%%%%