Fixed a bug that appears on preview due to short file name

[SebasMag]

Fixed a bug that appears on preview when a .js files has a 2 or less name length

Fixes #1413
#1413

I have verified that this pull request:

• has no linting errors (npm run lint)
• is from a uniquely-named feature branch and has been rebased on top of the latest master. (If I was asked to make more changes, I have made sure to rebase onto master then too). I had some issues with this
• is descriptively named and links to an issue number, i.e. Fixes #123

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[catarak]

Thank you! This is working great for me.