Resolve Application.isEditor once

This will prevent spamming of "Use isEditor in Awake" in debug builds

BepInEx/Bootstrap/Chainloader.cs

@@ -45,6 +45,14 @@ namespace BepInEx.Bootstrap
 			[MethodImpl(MethodImplOptions.NoInlining)]
 			get => SystemInfo.graphicsDeviceType == GraphicsDeviceType.Null;
 		}
+
+		// Check above for NoInlining reasoning
+		private static bool? isEditor;
+		internal static bool IsEditor
+		{
+			[MethodImpl(MethodImplOptions.NoInlining)]
+			get => isEditor ?? (isEditor = Application.isEditor) ?? false;
+		}
 		
 		/// <summary>
 		/// List of all <see cref="BepInPlugin"/> loaded via the chainloader.

BepInEx/Contract/BaseUnityPlugin.cs

@@ -36,7 +36,7 @@ namespace BepInEx
 			if(metadata == null)
 				throw new InvalidOperationException("Can't create an instance of " + GetType().FullName + " because it inherits from BaseUnityPlugin and the BepInPlugin attribute is missing.");
 
-			if (!Application.isEditor && Chainloader.PluginInfos.TryGetValue(metadata.GUID, out var info))
+			if (!Chainloader.IsEditor && Chainloader.PluginInfos.TryGetValue(metadata.GUID, out var info))
 				Info = info;
 			else
 			{
@@ -52,7 +52,7 @@ namespace BepInEx
 
 			Logger = Logging.Logger.CreateLogSource(metadata.Name);
 
-			string configRoot = Application.isEditor ? "." : Paths.ConfigPath;
+			string configRoot = Chainloader.IsEditor ? "." : Paths.ConfigPath;
 			Config = new ConfigFile(Utility.CombinePaths(configRoot, metadata.GUID + ".cfg"), false, metadata);
 		}
 	}