Step 1: Describe your environment

• Xcode version: 12.4 (12D4e)
• Firebase SDK version: 7.10.0
• Installation method: CocoaPods
• Firebase Component: Database

Step 2: Describe the problem

Database method reference(withPath:) (https://firebase.google.com/docs/reference/swift/firebasedatabase/api/reference/Classes/Database?authuser=0#referencewithpath:) crashes in case of simultaneous call from different threads. Reproduced in 90% of cases.

Steps to reproduce & Relevant Code: