TPSProjectEditor modifies the values of properties: [ bStrictConformanceMode ]. This is not allowed, as TPSProjectEditor has build products in common with UnrealEditor.
Remove the modified setting, change TPSProjectEditor to use a unique build environment by setting 'BuildEnvironment = TargetBuildEnvironment.Unique;' in the TPSProjectEditorTarget constructor, or set bOverrideBuildEnvironment = true to force this setting on.