This is an Android shipping build with everything I can stripped out. The component referenced is using constructor helpers to find editor only objects.
static ConstructorHelpers::FObjectFinder<UStaticMesh> PlaneMesh(TEXT("/Engine/ArtTools/RenderToTexture/Meshes/S_1_Unit_Plane.S_1_Unit_Plane"));
FocusPlaneVisualizationMesh = PlaneMesh.Object;
static ConstructorHelpers::FObjectFinder<UMaterial> PlaneMat(TEXT("/Engine/EngineDebugMaterials/M_SimpleTranslucent.M_SimpleTranslucent"));
FocusPlaneVisualizationMaterial = PlaneMat.Object;
Not sure if this is in 4.21 as my project can’t launch (other bug submitted, I’m at a loss so far) so I reverted to 4.20.