Error: Invalid version passed: 8.
   at forEach.version (/app/server/util/version.js:36:19)
   at Array.forEach (<anonymous>)
   at compareTo (/app/server/util/version.js:34:26)
   at Object.exports.greaterThanEqual (/app/server/util/version.js:31:52)
   at Object.exports.checkForSlugRedirect (/app/server/util/retired-docs.js:16:21)
   at exports.redirectRetiredIndividualDocs (/app/server/controllers/redirect.js:20:38)
   at Layer.handle [as handle_request] (/app/node_modules/express/lib/router/layer.js:82:5)
   at next (/app/node_modules/express/lib/router/route.js:100:13)
   at Route.dispatch (/app/node_modules/express/lib/router/route.js:81:3)
   at Layer.handle [as handle_request] (/app/node_modules/express/lib/router/layer.js:82:5)