Bug APIUpdater encountered some issues and was not able to finish.

I have a old project I've updated over the years and it regularly throws up the prompt asking to auto upgrade outdated api, there's no error if you hit no, but if you hit yes it throws an error. Then periodically throw that prompt again.

Currently on 2020.3.25f1.

To my knowledge there is no outdated api in the project. There are no errors and I don't write old api since it changed.

The error it throws:

Code (CSharp):

1. APIUpdater encountered some issues and was not able to finish.
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4.     System.ArgumentException: An item with the same key has already been added. Key: Hashtable
5.       at System.Collections.Generic.Dictionary`2[TKey,TValue].TryInsert (TKey key, TValue value, System.Collections.Generic.InsertionBehavior behavior) [0x000c1] in <695d1cc93cca45069c528c15c9fdd749>:0
6.       at System.Collections.Generic.Dictionary`2[TKey,TValue].Add (TKey key, TValue value) [0x00000] in <695d1cc93cca45069c528c15c9fdd749>:0
7.       at CSharpUpdater.Steps.NamespaceChanger.VisitUsingDirective (Microsoft.CodeAnalysis.CSharp.Syntax.UsingDirectiveSyntax node) [0x0002d] in <2160e9e537554ac5806788f5fe67a2fb>:0
8.       at Microsoft.CodeAnalysis.CSharp.Syntax.UsingDirectiveSyntax.Accept (Microsoft.CodeAnalysis.CSharp.CSharpSyntaxVisitor visitor) [0x00000] in <210537d4688541d39a6659ebe34ce496>:0
9.       at Microsoft.CodeAnalysis.CSharp.CSharpSyntaxWalker.Visit (Microsoft.CodeAnalysis.SyntaxNode node) [0x0001c] in <210537d4688541d39a6659ebe34ce496>:0
10.       at Microsoft.CodeAnalysis.CSharp.CSharpSyntaxWalker.DefaultVisit (Microsoft.CodeAnalysis.SyntaxNode node) [0x00038] in <210537d4688541d39a6659ebe34ce496>:0
11.       at Microsoft.CodeAnalysis.CSharp.CSharpSyntaxVisitor.VisitNamespaceDeclaration (Microsoft.CodeAnalysis.CSharp.Syntax.NamespaceDeclarationSyntax node) [0x00000] in <210537d4688541d39a6659ebe34ce496>:0
12.       at Microsoft.CodeAnalysis.CSharp.Syntax.NamespaceDeclarationSyntax.Accept (Microsoft.CodeAnalysis.CSharp.CSharpSyntaxVisitor visitor) [0x00000] in <210537d4688541d39a6659ebe34ce496>:0
13.       at Microsoft.CodeAnalysis.CSharp.CSharpSyntaxWalker.Visit (Microsoft.CodeAnalysis.SyntaxNode node) [0x0001c] in <210537d4688541d39a6659ebe34ce496>:0
14.       at Microsoft.CodeAnalysis.CSharp.CSharpSyntaxWalker.DefaultVisit (Microsoft.CodeAnalysis.SyntaxNode node) [0x00038] in <210537d4688541d39a6659ebe34ce496>:0
15.       at Microsoft.CodeAnalysis.CSharp.CSharpSyntaxVisitor.VisitCompilationUnit (Microsoft.CodeAnalysis.CSharp.Syntax.CompilationUnitSyntax node) [0x00000] in <210537d4688541d39a6659ebe34ce496>:0
16.       at CSharpUpdater.Steps.NamespaceChanger.VisitCompilationUnit (Microsoft.CodeAnalysis.CSharp.Syntax.CompilationUnitSyntax node) [0x00001] in <2160e9e537554ac5806788f5fe67a2fb>:0
17.       at Microsoft.CodeAnalysis.CSharp.Syntax.CompilationUnitSyntax.Accept (Microsoft.CodeAnalysis.CSharp.CSharpSyntaxVisitor visitor) [0x00000] in <210537d4688541d39a6659ebe34ce496>:0
18.       at Microsoft.CodeAnalysis.CSharp.CSharpSyntaxWalker.Visit (Microsoft.CodeAnalysis.SyntaxNode node) [0x0001c] in <210537d4688541d39a6659ebe34ce496>:0
19.       at CSharpUpdater.CSharpUpdater.RunUpdater (APIUpdater.Framework.Core.SourceFile[] inputs, APIUpdater.Framework.Core.UpdaterParameters parameters) [0x00145] in <2160e9e537554ac5806788f5fe67a2fb>:0
20.       at APIUpdater.Framework.Core.APIUpdaterBase.Update (APIUpdater.Framework.Core.SourceFile[] inputs, APIUpdater.Framework.Core.UpdaterParameters parameters) [0x0002c] in <173f4b68dfcb4aa58ee1627c2fca56d5>:0
21.       at ScriptUpdater.Program.UpdateLanguage (APIUpdater.Framework.Core.IScriptUpdater updater, APIUpdater.Framework.Configuration.CompilerResponseFile responseFile, System.String unityDataPath, System.String pathMappingFilePath, System.String outputPath) [0x0008c] in <7560b45d55864aacbd49d0afd54db505>:0
22.       at ScriptUpdater.Program.Main (System.String[] args) [0x000c8] in <7560b45d55864aacbd49d0afd54db505>:0