message: fix recently introduced crash on init
  certain material properties can only be set if supported by the
  material.
diff: @@ -80,11 +80,14 @@ FMaterialInstance::FMaterialInstance(FEngine& engine,
  setDoubleSided(mIsDoubleSided);
  }
  + if (material->getBlendingMode() == BlendingMode::MASKED) {
  setMaskThreshold(mMaskThreshold);
  + }
  + if (material->hasSpecularAntiAliasing()) {
  setSpecularAntiAliasingThreshold(mSpecularAntiAliasingThreshold);
  -
  setSpecularAntiAliasingVariance(mSpecularAntiAliasingVariance);
  + }
  setTransparencyMode(material->getTransparencyMode());
  