Source field question

[TotalCoolness]

Are the source fields compulsory now ? Before it would look for either the source fields and if it found one of them it would use it. Now it seems to want BOTH fields in the deck. If a deck doesn't have both fields it will crash.

Is possible to get the old behavior back where it looks for either field.

"source": [
    "Kanji_fields",
    "Expression"
],