On importing "UnityIAP" Package from "Unity IAP Installer" then it causes the Editor to throw "Assertion failed on expression" error, refer attached video.

To repro this issue:
1. Create a new project
2. Window > Package Manager > In App Purchasing package > Install
3. Edit > Project Settings > Services > In-App Purchasing > ON
4. Import the package > Unity IAP Installer > Install Now
5. Unity IAP Installer > Next > Import Unity Package(UDP) > Import
6. API Update Requierd > I Made a Backup, Go Ahed! > Select
7. Unity IAP Installer > Next > Import Unity Package(UnityIAP) > Import

Actual Result:
"Assertion failed on expression" error is thrown when "UnityIAP" Package imported from "Unity IAP Installer"

Expected Result:
UnityIAP Package is imported gracefully

Occurring in:
2020.2.0a15, 2020.1.0b12, 2020.1.0a23 with package version 2.0.6, 2.0.3, 2.0.0

Working fine in:
2020.1.0a22, 2019.3.15f1 with package version 2.0.6, 2.0.3, 2.0.0

Environment:
Windows10 and macOS 10.14

Stack trace:
Assertion failed on expression: 'ins.second || ins.first->second == artifactID || (ins.first->second == CircularDependencyArtifactID() && !artifactID.IsValid()) || GetPathFromAssetGuidV2(key.GetGUID()).ends_with(".cs")'
UnityEditor.AssemblyHelper:ExtractAllClassesThatAreUserExtendedScripts (string,string[]&,string[]&,string[]&)