CSV exporter throws error

reproduction steps

• Clone the adblockplusui project
• Checkout release-2018-4 branch
• Run csv-exporter node build/csv-export.js
• Observe

Observed behavior

Error below is being thrown:

UnhandledPromiseRejectionWarning: TypeError: Cannot convert undefined or null to object
    at Function.keys (<anonymous>)
    at csvFromJsonFileObjects (/Users/manvelsaroyan/projects/abp/adblockplusui/translations/build/csv-export.js:84:35)
    at <anonymous>

Expected behavior

No error is thrown

Note:

The issue arise after renaming the firstRun.json to first-run.json we currently generate DefaultLocale Rows for each file, so that includes also firstRun.json which basically doesn't exist for the DefaultLocale, the only solution I can see is that we only generate rows for the files that exist in the DefaultLocale folder.