An error occurring in MCS https://logstash.wikimedia.org/goto/9e8cfbb8abc110869e05b385c7b8a040\
```
TypeError: Cannot read property 'type' of undefined
at TokenStreamBase.LA (/srv/deployment/mobileapps/deploy-cache/revs/db795eca951a4377df87639fae4f86378fbd3a38/node_modules/domino/lib/cssparser.js:810:29)
at TokenStreamBase.advance (/srv/deployment/mobileapps/deploy-cache/revs/db795eca951a4377df87639fae4f86378fbd3a38/node_modules/domino/lib/cssparser.js:683:20)
at Parser._readDeclarations (/srv/deployment/mobileapps/deploy-cache/revs/db795eca951a4377df87639fae4f86378fbd3a38/node_modules/domino/lib/cssparser.js:3402:42)
at Parser.parseStyleAttribute (/srv/deployment/mobileapps/deploy-cache/revs/db795eca951a4377df87639fae4f86378fbd3a38/node_modules/domino/lib/cssparser.js:3581:22)
at parseStyles (/srv/deployment/mobileapps/deploy-cache/revs/db795eca951a4377df87639fae4f86378fbd3a38/node_modules/domino/lib/CSSStyleDeclaration.js:23:10)
at Object.get (/srv/deployment/mobileapps/deploy-cache/revs/db795eca951a4377df87639fae4f86378fbd3a38/node_modules/domino/lib/CSSStyleDeclaration.js:38:28)
at Object.value (/srv/deployment/mobileapps/deploy-cache/revs/db795eca951a4377df87639fae4f86378fbd3a38/node_modules/domino/lib/CSSStyleDeclaration.js:94:16)
at Object.get (/srv/deployment/mobileapps/deploy-cache/revs/db795eca951a4377df87639fae4f86378fbd3a38/node_modules/domino/lib/CSSStyleDeclaration.js:562:19)
at Object.closestInlineStyle (/srv/deployment/mobileapps/deploy-cache/revs/db795eca951a4377df87639fae4f86378fbd3a38/node_modules/wikimedia-page-library/build/wikimedia-page-library-transform.js:1:2235)
at s (/srv/deployment/mobileapps/deploy-cache/revs/db795eca951a4377df87639fae4f86378fbd3a38/node_modules/wikimedia-page-library/build/wikimedia-page-library-transform.js:1:23977)
at Array.filter (native)
at Object.classifyElements (/srv/deployment/mobileapps/deploy-cache/revs/db795eca951a4377df87639fae4f86378fbd3a38/node_modules/wikimedia-page-library/build/wikimedia-page-library-transform.js:1:24277)
at Object.module.exports [as prepForTheme] (/srv/deployment/mobileapps/deploy-cache/revs/db795eca951a4377df87639fae4f86378fbd3a38/src/lib/transformations/pcs/prepForTheme.js:11:20)
at _processChunked (/srv/deployment/mobileapps/deploy-cache/revs/db795eca951a4377df87639fae4f86378fbd3a38/src/lib/processing.js:34:29)
at chunk.forEach.i (/srv/deployment/mobileapps/deploy-cache/revs/db795eca951a4377df87639fae4f86378fbd3a38/src/lib/processing.js:28:58)
at Array.forEach (native)
at Immediate.setImmediate (/srv/deployment/mobileapps/deploy-cache/revs/db795eca951a4377df87639fae4f86378fbd3a38/src/lib/processing.js:28:45)
at runCallback (timers.js:672:20)
at tryOnImmediate (timers.js:645:5)
at processImmediate [as _immediateCallback] (timers.js:617:5)
```
A big issue is that it goes unhandled and gets caught by service-runner unhandled exception handler.