From log file in production. Having a hard time reproducing the same in a local dev environment).
```
500: internal_error (message="500: internal_error", status=500, type=internal_error, detail="Cannot read property 'indexOf' of undefined", levelPath=error/500, request_id=a3d71ed3-9406-11e7-8e78-11414b1d2af5)
stack: TypeError: Cannot read property 'indexOf' of undefined
at sections.forEach (/srv/deployment/mobileapps/deploy-cache/revs/507a479c96953ff0b3fa5ba12472b0c56570c138/src/lib/transformations/markReferenceSections.js:34:17)
at Array.forEach (native)
at Object.markReferenceSections (/srv/deployment/mobileapps/deploy-cache/revs/507a479c96953ff0b3fa5ba12472b0c56570c138/src/lib/transformations/markReferenceSections.js:26:14)
at buildRemaining (/srv/deployment/mobileapps/deploy-cache/revs/507a479c96953ff0b3fa5ba12472b0c56570c138/src/routes/mobile-sections.js:161:20)
at buildAll (/srv/deployment/mobileapps/deploy-cache/revs/507a479c96953ff0b3fa5ba12472b0c56570c138/src/routes/mobile-sections.js:194:20)
at _collectRawPageData.then (/srv/deployment/mobileapps/deploy-cache/revs/507a479c96953ff0b3fa5ba12472b0c56570c138/src/routes/mobile-sections.js:323:20)
at tryCatcher (/srv/deployment/mobileapps/deploy-cache/revs/507a479c96953ff0b3fa5ba12472b0c56570c138/node_modules/bluebird/js/release/util.js:16:23)
at Promise._settlePromiseFromHandler (/srv/deployment/mobileapps/deploy-cache/revs/507a479c96953ff0b3fa5ba12472b0c56570c138/node_modules/bluebird/js/release/promise.js:512:31)
at Promise._settlePromise (/srv/deployment/mobileapps/deploy-cache/revs/507a479c96953ff0b3fa5ba12472b0c56570c138/node_modules/bluebird/js/release/promise.js:569:18)
at Promise._settlePromise0 (/srv/deployment/mobileapps/deploy-cache/revs/507a479c96953ff0b3fa5ba12472b0c56570c138/node_modules/bluebird/js/release/promise.js:614:10)
at Promise._settlePromises (/srv/deployment/mobileapps/deploy-cache/revs/507a479c96953ff0b3fa5ba12472b0c56570c138/node_modules/bluebird/js/release/promise.js:693:18)
at Promise._fulfill (/srv/deployment/mobileapps/deploy-cache/revs/507a479c96953ff0b3fa5ba12472b0c56570c138/node_modules/bluebird/js/release/promise.js:638:18)
at Promise._resolveCallback (/srv/deployment/mobileapps/deploy-cache/revs/507a479c96953ff0b3fa5ba12472b0c56570c138/node_modules/bluebird/js/release/promise.js:432:57)
at Promise._settlePromiseFromHandler (/srv/deployment/mobileapps/deploy-cache/revs/507a479c96953ff0b3fa5ba12472b0c56570c138/node_modules/bluebird/js/release/promise.js:524:17)
at Promise._settlePromise (/srv/deployment/mobileapps/deploy-cache/revs/507a479c96953ff0b3fa5ba12472b0c56570c138/node_modules/bluebird/js/release/promise.js:569:18)
at Promise._settlePromise0 (/srv/deployment/mobileapps/deploy-cache/revs/507a479c96953ff0b3fa5ba12472b0c56570c138/node_modules/bluebird/js/release/promise.js:614:10)
at Promise._settlePromises (/srv/deployment/mobileapps/deploy-cache/revs/507a479c96953ff0b3fa5ba12472b0c56570c138/node_modules/bluebird/js/release/promise.js:693:18)
at Promise._fulfill (/srv/deployment/mobileapps/deploy-cache/revs/507a479c96953ff0b3fa5ba12472b0c56570c138/node_modules/bluebird/js/release/promise.js:638:18)
at PropertiesPromiseArray.PromiseArray._resolve (/srv/deployment/mobileapps/deploy-cache/revs/507a479c96953ff0b3fa5ba12472b0c56570c138/node_modules/bluebird/js/release/promise_array.js:126:19)
--
request: {
"url": "/fr.wikipedia.org/v1/page/mobile-sections/Portail%3ABaroque",
...
"method": "GET",
"params": {
"0": "/fr.wikipedia.org/v1/page/mobile-sections/Portail:Baroque"
},
...
}
```
So, to repro run this on one of the production boxes:
```
curl http://localhost:8888/fr.wikipedia.org/v1/page/mobile-sections/Portail:Baroque
{"status":500,"type":"internal_error","title":"TypeError","detail":"Cannot read property 'indexOf' of undefined","method":"GET","uri":"/fr.wikipedia.org/v1/page/mobile-sections/Portail:Baroque"}
```
Another example: http://localhost:8888/fy.wikipedia.org/v1/page/mobile-sections/De_Kanto%27s