Fix for untitled projects in picker tile sizes

[ifeLawal]

I saw this open in the good first issue and thought it would be a good first tackle as a relatively new programmer.

My approach was to adjust the empty string fallback that gets returned from the generateTextPreview() method. I had 2 possible thoughts

• Make the fallback "Page Title", since this is the starting page title for the new page
• Use a space regular expression, "\b" or "\s" as the fallback so it keeps the empty look but fills the space where text would exist

I went with the regular expression approach since it looks empty, which matches what would be in a students <Title> tag in the html on Popcode. I used the same approach for the time section in the tile, but I was not sure how to reproduce the time actually being an empty string so any feedback on your thoughts on reproducing this, as well as if the regular expression approach makes sense, would be super helpful.

Closes #2102

[ifeLawal]

@outoftime Sorry I don't see the + next to Reviewers to add you as a reviewer