Prevent user error when incorrectly formatted footnotes are added to …

…HTML attachments

When footnotes are used in HTML attachments, this function would cause an unhelpful user error to be displayed. This will allow the attachment to save.

Example of incorrectly formatted footnotes:

[^22]: CDC. Centre for Disease Control and Prevention. Invasive Mold Infections in Immunocompromised People [updated 06/06/2019]. Available from: Invasive Mold Infections in Immunocompromised People | Mold | CDC
23. David J. Pevalin, Aaron Reeves, Emma Baker, Rebecca Bentley, The impact of persistent poor housing conditions on mental health: A longitudinal population-based study, Preventive Medicine, Volume 105, 2017, Pages 304-310, https://doi.org/10.1016/j.ypmed.2017.09.020

22 contains the character | which triggers table formatting. 23 is not correctly formatted as a footnote.

Co-authored-by: Bruce Bolt <bruce.bolt@digital.cabinet-office.gov.uk>

CHANGELOG.md

@@ -1,3 +1,7 @@
+## Unreleased
+
+* Prevent user error when incorrectly formatted footnotes are added to HTML attachments ([#287](https://github.com/alphagov/govspeak/pull/287))
+
 ## 8.2.0
 
 * Reintroduce support for acronyms in Call To Action blocks and in Legislative Lists ([#285](https://github.com/alphagov/govspeak/pull/285))

lib/govspeak.rb

@@ -451,6 +451,8 @@ def encode(text)
     end
 
     def add_acronym_alt_text(html)
+      return unless html
+
       @acronyms.each do |acronym|
         html.gsub!(acronym[0], "<abbr title=\"#{acronym[1].strip}\">#{acronym[0]}</abbr>")
       end