Enhance error message

Assets/StreetLight/Scripts/PersonManager.cs

@@ -29,7 +29,7 @@ namespace Assets.StreetLight.Scripts
             }
             catch (Exception ex)
             {
-                Debug.LogError($"Could not load homography: {ex.Message}");
+                Debug.LogWarning($"Could not load homography: {ex.Message}. Calculating the unity position of a person will not be possible. (This is expected during calibration.)");
             }
 
             Persons = new ObservableCollection<Person>();