Warning: LaTeX Warning: Reference `fig:coda-plots' on page 57 undefined on input line 2600.

Hi.I have found a warning"Warning: LaTeX Warning: Reference `fig:coda-plots' on page 57 undefined on input line 2600",which is in [part-01-04-ergms.Rmd](https://github.com/gvegayon/appliedsnar/blob/master/part-01-04-ergms.Rmd) line 408.Could you tell me how to fix this?Thanks!