Unity2019でAdmobSDKをインポートしたらエディタがエラーしたり無限ループしたり

Unity2019.1 AdmobSDK : 3.18.2

の環境でエディタで下記のようなエラーが出力される。

Stopped polling job due to exception: System.MissingMethodException: UnityEditor.VersionControl.Task UnityEditor.VersionControl.Provider.Checkout(string,UnityEditor.VersionControl.CheckoutMode)
  at Google.ProjectSettings.Set[T] (System.String name, T value) [0x00024] in /Users/smiles/dev/src/unity-jar-resolver/source/VersionHandlerImpl/src/ProjectSettings.cs:119 
  at Google.ProjectSettings+<SetBool>c__AnonStorey2.<>m__5 () [0x00000] in /Users/smiles/dev/src/unity-jar-resolver/source/VersionHandlerImpl/src/ProjectSettings.cs:154 
  at Google.ProjectSettings.SavePreferences (Google.ProjectSettings+SettingsSave saveLevel, System.Action saveToProject, System.Action saveToEditor) [0x00035] in /Users/smiles/dev/src/unity-jar-resolver/source/VersionHandlerImpl/src/ProjectSettings.cs:135 
  at Google.ProjectSettings.SetBool (System.String name, System.Boolean value) [0x00014] in /Users/smiles/dev/src/unity-jar-resolver/source/VersionHandlerImpl/src/ProjectSettings.cs:153 
  at GooglePlayServices.SettingsDialog.set_UseJetifier (System.Boolean value) [0x00000] in /Users/smiles/dev/src/unity-jar-resolver/source/PlayServicesResolver/src/SettingsDialog.cs:225 
  at GooglePlayServices.PlayServicesResolver.CanEnableJetifierOrPromptUser (System.String titlePrefix) [0x00179] in /Users/smiles/dev/src/unity-jar-resolver/source/PlayServicesResolver/src/PlayServicesResolver.cs:2270 
  at GooglePlayServices.PlayServicesResolver.ResolveUnsafe (System.Action`1[T] resolutionComplete, System.Boolean forceResolution, System.Boolean isAutoResolveJob, System.Boolean closeWindowOnCompletion) [0x00012] in /Users/smiles/dev/src/unity-jar-resolver/source/PlayServicesResolver/src/PlayServicesResolver.cs:1610 
  at GooglePlayServices.PlayServicesResolver+<ScheduleResolve>c__AnonStorey1E.<>m__40 () [0x00000] in /Users/smiles/dev/src/unity-jar-resolver/source/PlayServicesResolver/src/PlayServicesResolver.cs:1579 
  at GooglePlayServices.PlayServicesResolver.ExecuteNextResolveJob () [0x00069] in /Users/smiles/dev/src/unity-jar-resolver/source/PlayServicesResolver/src/PlayServicesResolver.cs:1438 
  at GooglePlayServices.PlayServicesResolver.ScheduleResolve (System.Boolean forceResolution, System.Boolean closeWindowOnCompletion, System.Action`1[T] resolutionCompleteWithResult, System.Boolean isAutoResolveJob) [0x000a7] in /Users/smiles/dev/src/unity-jar-resolver/source/PlayServicesResolver/src/PlayServicesResolver.cs:1592 
  at GooglePlayServices.PlayServicesResolver.AutoResolve (System.Action resolutionComplete) [0x00017] in /Users/smiles/dev/src/unity-jar-resolver/source/PlayServicesResolver/src/PlayServicesResolver.cs:1113 
  at GooglePlayServices.PlayServicesResolver.<ScheduleAutoResolve>m__48 () [0x00016] in /Users/smiles/dev/src/unity-jar-resolver/source/PlayServicesResolver/src/PlayServicesResolver.cs:1092 
  at Google.RunOnMainThread.ExecutePollingJobs () [0x0004a] in /Users/smiles/dev/src/unity-jar-resolver/source/VersionHandlerImpl/src/RunOnMainThread.cs:300 
UnityEngine.Debug:LogError(Object)
Google.RunOnMainThread:ExecutePollingJobs() (at /Users/smiles/dev/src/unity-jar-resolver/source/VersionHandlerImpl/src/RunOnMainThread.cs:303)
Google.RunOnMainThread:<ExecuteAll>m__17() (at /Users/smiles/dev/src/unity-jar-resolver/source/VersionHandlerImpl/src/RunOnMainThread.cs:414)
Google.RunOnMainThread:RunAction(Action) (at /Users/smiles/dev/src/unity-jar-resolver/source/VersionHandlerImpl/src/RunOnMainThread.cs:234)
Google.RunOnMainThread:ExecuteAll() (at /Users/smiles/dev/src/unity-jar-resolver/source/VersionHandlerImpl/src/RunOnMainThread.cs:406)
UnityEditor.EditorApplication:Internal_CallUpdateFunctions()

ここに解決法があった

Stopped polling job due to exception: System.MissingMethodException: UnityEditor.VersionControl.Task · Issue #262 · googlesamples/unity-jar-resolver · GitHub

unity-jar-resolver を更新する

Release v1.2.124: Version 1.2.124 · googlesamples/unity-jar-resolver · GitHub