Editor throws null reference exception on making build any platform.

Steps To Reproduce:

1. Launch the editor.
2. Go to File -> Build Settings
3. Make the build for any platform.
4. Observe that 'Null reference' error is thrown as soon as the build is made.

Note: The build is made successfully even after the null reference exception.

Working fine on : 2018.3.a3, 2018.2.0b11

Occurs on: 2018.3.0a4

Environment:

Windows and Mac

Stack Trace :

NullReferenceException: Object reference not set to an instance of an object
UnityEditor.BuildPlayerWindow+DefaultBuildMethods.BuildPlayer (BuildPlayerOptions options) (at /Users/builduser/buildslave/unity/build/Editor/Mono/BuildPlayerWindowBuildMethods.cs:196)
UnityEditor.BuildPlayerWindow.CallBuildMethods (Boolean askForBuildLocation, BuildOptions defaultBuildOptions) (at /Users/builduser/buildslave/unity/build/Editor/Mono/BuildPlayerWindowBuildMethods.cs:96)
UnityEditor.BuildPlayerWindow.GUIBuildButtons (IBuildWindowExtension buildWindowExtension, Boolean enableBuildButton, Boolean enableBuildAndRunButton, Boolean canInstallInBuildFolder, UnityEditor.Build.BuildPlatform platform) (at /Users/builduser/buildslave/unity/build/Editor/Mono/BuildPlayerWindow.cs:914)
UnityEditor.BuildPlayerWindow.ShowBuildTargetSettings () (at /Users/builduser/buildslave/unity/build/Editor/Mono/BuildPlayerWindow.cs:823)
UnityEditor.BuildPlayerWindow.OnGUI () (at /Users/builduser/buildslave/unity/build/Editor/Mono/BuildPlayerWindow.cs:422)
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MonoMethod.cs:222)
Rethrow as TargetInvocationException: Exception has been thrown by the target of an invocation.
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MonoMethod.cs:232)
System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MethodBase.cs:115)
UnityEditor.HostView.Invoke (System.String methodName, System.Object obj) (at /Users/builduser/buildslave/unity/build/Editor/Mono/HostView.cs:323)
UnityEditor.HostView.Invoke (System.String methodName) (at /Users/builduser/buildslave/unity/build/Editor/Mono/HostView.cs:317)
UnityEditor.HostView.OldOnGUI () (at /Users/builduser/buildslave/unity/build/Editor/Mono/HostView.cs:118)
UnityEngine.Experimental.UIElements.IMGUIContainer.DoOnGUI (UnityEngine.Event evt, Matrix4x4 worldTransform, Rect clippingRect, Boolean isComputingLayout) (at /Users/builduser/buildslave/unity/build/Modules/UIElements/IMGUIContainer.cs:237)