To Reproduce:

1. Open the attached project and click "Test/Bug" in the menu to call:

PlayerSettings.SetScriptingDefineSymbolsForGroup(
BuildTargetGroup.Android, PlayerSettings.GetScriptingDefineSymbolsForGroup(BuildTargetGroup.Android)
);

2. Observe that it fails with :

PlayerSettings Validation: Requested build target group (25) doesn't exist; #define symbols for scripting won't be added.
UnityEditor.PlayerSettings:SetScriptingDefineSymbolsForGroup(BuildTargetGroup, String)
Bug:Foo() (at Assets/Editor/Bug.cs:9)