Step 0: Are you in the right place?

• For issues or feature requests related to the code in this repository
  file a Github issue.
  • If this is a feature request please use the Feature Request template.
• For general technical questions, post a question on StackOverflow
  with the firebase tag.
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  google group.
• For backend issues, console issues, and other non-SDK help that does not fall under one
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• Once you've read this section and determined that your issue is appropriate for
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[REQUIRED] Step 1: Describe your environment

• Xcode version: 12.3
• Firebase SDK version: 7.2.0
• Installation method: CocoaPods
• Firebase Component: Storage

[REQUIRED] Step 2: Describe the problem

Steps to reproduce:

• Create a ref for a cloud storage folder the current user cannot list items.
• Call listAllWithCompletion on this StorageRef
• Notice the completion helper is called twice: once with the permission denied error, the other time with an empty directory result.

Relevant Code:

Sorry, I suck at ObjC, here's a reproduction with the RNFirebase SDK invertase/react-native-firebase#4688

This issue can be summed up in one question: Is there a missing return here:

... Or did you intend to call the completion helper with the files you got so far if an error occurs?

Since this seems to differ with the behaviour on Android (where the Task class will not allow you to reject and resolve the same task, I think?), I think adding a warning in the documentation could help anyway.