Unityで制作中のゲームで、AdMobを入れたらエラーが出るようになった

Unityでandroid向けゲームを作り、AdMobを入れてバナー広告を出せるように作業していたのですが
気付いたらコンソールにエラーが出ており、当方初心者なので恥ずかしながら
何が原因でどう対処すればいいのかすら分かりません。
何卒ご教授のほど、お願いできませんでしょうか。

発生している問題・エラーメッセージ

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()