Xcodeをアップデートしたらstoryboardがおかしくなった

前提・実現したいこと

xcodeのstoryboradを使えるようにしたい(update前と同じような作業環境にしたい)です。

xcodeを10.3にアップデートしました。
アップデートが完了してxcodeを開くとポップアップウィンドウ(?)のようなものが出てきて
"install" / "quit" の２択だったのでインストールを選択しました。
(インストール内容はよく読まずにインストールしてしまいました orz )
インストールを終えてxcodeを開くとこのような状況になっていました。

↓上から順に、xcode内のエラーメッセージ、log内のエラーメッセージです。

発生している問題・エラーメッセージ

file:///Users/otoy/Mydictionary/MyDictionary/Base.lproj/Main.storyboard: error: IB Designables: Failed to render and update auto layout status for NewNoteViewController (iIJ-cw-XLr): Failed to launch designables agent. Check the console for a more detailed description and please file a bug report at bugreport.apple.com.

Failed to find or create execution context for description '<IBCocoaTouchPlatformToolDescription: 0x7faf09411990> System content for IBCocoaTouchFramework-ElevenAndLater <IBSimulatorDeviceTypeDescription: 0x7faef2bdc2c0> deviceType=com.apple.CoreSimulator.SimDeviceType.iPhone-XS'. These intermediate objects were non-nil: (
    "iPhone Xs (com.apple.CoreSimulator.SimDeviceType.iPhone-XS)",
    "iOS 12.4 (12.4 - 16G73) - com.apple.CoreSimulator.SimRuntime.iOS-12-4"
): Failed to find a suitable device for the type iPhone Xs (com.apple.CoreSimulator.SimDeviceType.iPhone-XS) with runtime iOS 12.4 (12.4 - 16G73) - com.apple.CoreSimulator.SimRuntime.iOS-12-4 (Failure reason: Failed to create new simulator device that matches iPhone Xs (com.apple.CoreSimulator.SimDeviceType.iPhone-XS) for runtime iOS 12.4 (12.4 - 16G73) - com.apple.CoreSimulator.SimRuntime.iOS-12-4 (Invalid runtime: com.apple.CoreSimulator.SimRuntime.iOS-12-4)): Invalid runtime: com.apple.CoreSimulator.SimRuntime.iOS-12-4

Error Domain=com.apple.CoreSimulator.SimError Code=160 "Failed to find or create execution context for description '<IBCocoaTouchPlatformToolDescription: 0x7faf09411990> System content for IBCocoaTouchFramework-ElevenAndLater <IBSimulatorDeviceTypeDescription: 0x7faef2bdc2c0> deviceType=com.apple.CoreSimulator.SimDeviceType.iPhone-XS'. These intermediate objects were non-nil: (
    "iPhone Xs (com.apple.CoreSimulator.SimDeviceType.iPhone-XS)",
    "iOS 12.4 (12.4 - 16G73) - com.apple.CoreSimulator.SimRuntime.iOS-12-4"
)" UserInfo={NSLocalizedDescription=Failed to find or create execution context for description '<IBCocoaTouchPlatformToolDescription: 0x7faf09411990> System content for IBCocoaTouchFramework-ElevenAndLater <IBSimulatorDeviceTypeDescription: 0x7faef2bdc2c0> deviceType=com.apple.CoreSimulator.SimDeviceType.iPhone-XS'. These intermediate objects were non-nil: (
    "iPhone Xs (com.apple.CoreSimulator.SimDeviceType.iPhone-XS)",
    "iOS 12.4 (12.4 - 16G73) - com.apple.CoreSimulator.SimRuntime.iOS-12-4"
), NSUnderlyingError=0x7faf11ee7ee0 {Error Domain=com.apple.CoreSimulator.SimError Code=160 "Failed to find a suitable device for the type iPhone Xs (com.apple.CoreSimulator.SimDeviceType.iPhone-XS) with runtime iOS 12.4 (12.4 - 16G73) - com.apple.CoreSimulator.SimRuntime.iOS-12-4" UserInfo={NSLocalizedFailureReason=Failed to create new simulator device that matches iPhone Xs (com.apple.CoreSimulator.SimDeviceType.iPhone-XS) for runtime iOS 12.4 (12.4 - 16G73) - com.apple.CoreSimulator.SimRuntime.iOS-12-4 (Invalid runtime: com.apple.CoreSimulator.SimRuntime.iOS-12-4), NSLocalizedDescription=Failed to find a suitable device for the type iPhone Xs (com.apple.CoreSimulator.SimDeviceType.iPhone-XS) with runtime iOS 12.4 (12.4 - 16G73) - com.apple.CoreSimulator.SimRuntime.iOS-12-4, NSUnderlyingError=0x7faf1070f650 {Error Domain=com.apple.CoreSimulator.SimError Code=160 "Invalid runtime: com.apple.CoreSimulator.SimRuntime.iOS-12-4" UserInfo={NSLocalizedDescription=Invalid runtime: com.apple.CoreSimulator.SimRuntime.iOS-12-4}}}}}