Prevent crash if meta tag dig encounters wrong data structure/type

CHANGELOG.md

@@ -7,6 +7,10 @@
   useful summary for people upgrading their application, not a replication
   of the commit log.
 
+## Unreleased
+
+* Prevent crash if meta tag dig encounters wrong data structure/type ([PR #3741](https://github.com/alphagov/govuk_publishing_components/pull/3741))
+
 ## 36.0.1
 
 * Use component wrapper on option select ([PR #3738](https://github.com/alphagov/govuk_publishing_components/pull/3738))

lib/govuk_publishing_components/presenters/meta_tags.rb

@@ -90,7 +90,13 @@ def add_political_tags(meta_tags)
       # Some 'government' objects are nested in the content item on some pages. We want to grab these for GA4 tracking.
       # We only add the publishing government if 'political' is true, otherwise some content items get incorrectly linked to a government
       def add_ga4_political_tags(meta_tags)
-        government = content_item.dig(:links, :government, 0)
+        government = content_item.dig(:links, :government)
+
+        if government.is_a?(Array)
+          government = government[0]
+        else
+          return meta_tags
+        end
 
         # political: true/false is in a different place to current: true/false, which is why we have 'details' and 'government[:details]'
         if government && details[:political]

spec/components/meta_tags_spec.rb

@@ -464,6 +464,17 @@ def example_document_for(schema_name, example_name)
     assert_no_meta_tag("govuk:ga4-political-status")
   end
 
+  it "doesn't crash generating GA4 political tags if it tries to dig into 'government' when it can't" do
+    content_item = {
+      "links": {
+        "government": "i am not an array nor a hash, therefore it seems that i may crash",
+      },
+    }
+    render_component(content_item: example_document_for("html_publication", "published_with_history_mode").merge(content_item))
+    assert_no_meta_tag("govuk:ga4-publishing-government")
+    assert_no_meta_tag("govuk:ga4-political-status")
+  end
+
   it "doesn't render GA4 political tags if the government object exists in the content item, but political is false" do
     content_item = {
       "political": false,