Check the `[]dependency` slice length to avoid panic

[moadqassem]

What does this do / why do we need it?

It checks if a slice is nil or not and we need because the code will panic without it.

Do you need help or clarification on anything?

No

Which issue(s) does this PR fix?

fixes #2194

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[googlebot]

Thanks for your pull request. It looks like this may be your first contribution to a Google open source project (if not, look below for help). Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

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[moadqassem]

@googlebot I signed it!

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CLAs look good, thanks!

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CLAs look good, thanks!

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[mvdan]

Dep was officially deprecated earlier this year, and the proposal to archive this repository was accepted. As such, I'm closing outstanding issues before archiving the repository. For any further comments, please use the proposal thread on the Go issue tracker. Thanks!