# Unit 5 Hackathon - Why don't the lists fill?

**URL:** <https://forum.code.org/t/unit-5-hackathon-why-dont-the-lists-fill/36120>\
**Category:** Coding and Debugging Help\
**Tags:** csp-unit-5\
**Created:** [March 31, 2022, 11:17pm UTC](https://forum.code.org/t/unit-5-hackathon-why-dont-the-lists-fill/36120 "2022-03-31T23:17:46Z")\
**Posts on this page:** 1\
**Showing post:** 5

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**Author:** ![jdonwells](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.code.org/jdonwells/32/7900_2.png) [@jdonwells](https://forum.code.org/u/jdonwells)\
**Post date:** [April 2, 2022, 7:02pm UTC](https://forum.code.org/t/unit-5-hackathon-why-dont-the-lists-fill/36120/5 "2022-04-02T19:02:46Z")

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> [@getColumn: one common error and one subtle error explained](https://forum.code.org/t/getcolumn-one-common-error-and-one-subtle-error-explained/34355):
>
> The most common error with getColumn by far seems to be wrapping it in []s. You end up with an array (returned by getColumn) inside an array (created by []) and that doesn’t do what you want at all. So just write var cats = getColumn("Cats","Name");. No ( )s and no []s. I wrote a more complete explanation here [Everything You Wanted to Know About App Lab Arrays, But Were Afraid to Ask](https://forum.code.org/t/everything-you-wanted-to-know-about-app-lab-arrays-but-were-afraid-to-ask/34277). The subtle error that can result is a race condition. A race condition happens when you have two or more s…

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