Complicance overview fails if Crossref metadata lack funder's DOI

[fkohrt]

For cases where the Crossref metadata lack the funder's DOI, the compliance overview cannot be created:

biblids::as_doi("10.1098/rsos.221306") |>
  metacheck::get_cr_md() |>
  metacheck::cr_compliance_overview()

leads to the following error:

Error in `.data$DOI`:
! Column `DOI` not found in `.data`.
Run `rlang::last_error()` to see where the error occurred.

Only after adding the funder's DOI manually it works:

biblids::as_doi("10.1098/rsos.221306") |>
  metacheck::get_cr_md() |>
  within({
    funder[[1]]$DOI <- "10.13039/501100001659"
    funder[[1]]$doi.asserted.by <- NA_character_
  }) |>
  metacheck::cr_compliance_overview()