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.
• For general (non-iOS) Firebase discussion, use the firebase-talk
  google group.
• For backend issues, console issues, and other non-SDK help that does not fall under one
  of the above categories, reach out to
  Firebase Support.
• Once you've read this section and determined that your issue is appropriate for
  this repository, please delete this section.

[REQUIRED] Step 1: Describe your environment

• Xcode version: 12.0 (12A7209)
• Firebase SDK version: 6.34.0
• Firebase Component: Performance (Auth, Core, Database, Firestore, Messaging, Storage, etc)
• Component version: 3.3.1
• Installation method: CocoaPods

[REQUIRED] Step 2: Describe the problem

I've just updated Firebase Performance from 3.3.0 => 3.3.1 on iOS and my project is now crashing due to an exception while releasing a FPRNetorkTrace:

*** Terminating app due to uncaught exception 'NSRangeException', reason: 'Cannot remove an observer <FPRNetworkTrace 0x280e41c00> for the key path "state" from <__NSCFLocalDataTask 0x103c4a7b0> because it is not registered as an observer.
        0 CoreFoundation           0x00000001a2fde128 F80FCA31-BF76-3293-8BC6-1729588AE8B6 + 1155368
	1 libobjc.A.dylib          0x00000001b6804cb4 objc_exception_throw + 56
	2 Foundation             0x00000001a41a28e4 4B7B9C0A-BAD3-348D-95A3-94784BFED02E + 301284
	3 Foundation             0x00000001a41a2600 4B7B9C0A-BAD3-348D-95A3-94784BFED02E + 300544
	4 ClienteIOS             0x00000001015ab7d4 -[FPRNetworkTrace dealloc] + 176
	5 libsystem_blocks.dylib       0x00000001e7a75784 _Block_release + 188
	6 libdispatch.dylib         0x00000001034795fc _dispatch_client_callout + 16
	7 libdispatch.dylib         0x0000000103480878 _dispatch_lane_serial_drain + 1252
	8 libdispatch.dylib         0x0000000103481308 _dispatch_lane_invoke + 452
	9 libdispatch.dylib         0x000000010348cb34 _dispatch_workloop_worker_thread + 1456
	10 libsystem_pthread.dylib      0x00000001e7aec5a4 _pthread_wqthread + 272
	11 libsystem_pthread.dylib      0x00000001e7aef874 start_wqthread + 8

Podfile:

Uncomment the next line to define a global platform for your project

platform :ios, '9.0'

source 'https://github.com/CocoaPods/Specs.git'
target 'ClienteIOS' do

Comment the next line if you're not using Swift and don't want to use dynamic frameworks

use_frameworks!

Pods for ClienteIOS

pod 'GoogleMobileAdsMediationTestSuite'
#pod 'FBAudienceNetwork'
pod 'GoogleMobileAdsMediationFacebook'
pod 'Socket.IO-Client-Swift', :path=>'~/sio/'
#Pods for Facebook
pod 'FBSDKCoreKit'
pod 'FBSDKLoginKit'
pod 'FBSDKShareKit'
pod 'Bolts'
#Pods Firebase
pod 'Firebase/AdMob'
pod 'Firebase/Analytics'
pod 'Firebase/RemoteConfig'
pod 'Firebase/Performance'
pod 'Firebase/InAppMessaging'
pod 'FirebaseCrashlytics'
end
post_install do |installer|
installer.pods_project.build_configurations.each do |config|
config.build_settings['SWIFT_OPTIMIZATION_LEVEL'] = '-Onone';
end
end

Steps to reproduce:

It crashes shortly after finishing the first http request of the app (shortly meaning next dispatch, or something like that).