Sentry Template render error

[pooleycodes]

Sentry Issue: PROVIDE-15

TypeError: Cannot read properties of undefined (reading 'charAt')
  File "/app/src/filters/makeDatasetSlugToReadableNameFilter.js", line 19, in capitalizeFirst
    const capitalizeFirst = (str) => str.charAt(0).toUpperCase() + str.slice(1)
  File "/app/src/filters/makeDatasetSlugToReadableNameFilter.js", line 27
    return capitalize ? capitalizeFirst(slug) : lowercaseFirst(slug)
  File "/app/src/filters/filters.js", line 36, in Context.?
    nunjucksEnv.addFilter('datasetSlugToReadableName', (...args) => datasetSlugToReadableName(...args))
...
(5 additional frame(s) were not displayed)

Template render error: (/app/src/views/submit/check-answers.html) [Line 17, Column 3]
  TypeError: Cannot read properties of undefined (reading 'charAt')
  File "/app/node_modules/nunjucks/src/runtime.js", line 227, in Object.handleError
    return new lib.TemplateError(error, lineno, colno);
  File "eval at _compile (/app/node_modules/nunjucks/src/environment.js:527:18), <anonymous>", line 168, in b_content
  File "eval at _compile (/app/node_modules/nunjucks/src/environment.js:527:18), <anonymous>", line 285, in eval
  File "eval at _compile (/app/node_modules/nunjucks/src/environment.js:527:18), <anonymous>", line 106, in b_beforeContent
  File "eval at _compile (/app/node_modules/nunjucks/src/environment.js:527:18), <anonymous>", line 268, in b_main
...
(5 additional frame(s) were not displayed)