Tabs to spaces, rephrase log message

Source/Urho3D/Urho2D/StaticSprite2D.cpp

@@ -85,11 +85,12 @@ void StaticSprite2D::RegisterObject(Context* context)
 
 void StaticSprite2D::SetSprite(Sprite2D* sprite)
 {
-	if (!sprite)
-	{
-		URHO3D_LOGERROR("Sprite must not be null!");
-		return;
-	}
+    if (!sprite)
+    {
+        URHO3D_LOGERROR("Can not set null sprite");
+        return;
+    }
+
     if (sprite == sprite_)
         return;