TypeError: Cannot read properties of null (reading 'length')

[sentry]

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Observed behavior

QA on community channels triggered this error.

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Sentry Issue: STUDIO-J65

TypeError: Cannot read properties of null (reading 'length')
  at categoriesString (administration/components/sidePanels/ReviewSubmissionSidePanel.vue:365:1)
  at <object>.scopedSlots.fn (./administration/components/sidePanels/ReviewSubmissionSidePanel.vue:4:1208)
  at render (./shared/views/SidePanelModal/index.vue:3:434)
...
(11 additional frame(s) were not displayed)

Expected behavior

We might need some defensive checks on this, so we don't create Sentry noise.