Enum parsing. Use default value.

[brexGmbH]

Hi,
Luckily right before a big release we noticed a big problem in conversions with enums.
The problem is the following:
Lets assume we have an enum with the following values:

PlayerType: {Unknown, Player 1, Player 2, Player 3}
We created a struct that has these 4 options as well.
Now we release that version with the struct containing those 4 options.
After that we decide to implement a 4th player type (Player 4).
In the backend we add that player type, but our users still run the "old" unreal software.
These old clients receive a json response from the backend that can say PlayerType = Player 4.

If that is actually the case the plugin will throw an error and json2struct conversion fails completely, even if this was just one little thing in a big nested struct. We need it to use a default value instead, so we can handle unknown players.

I fixed it by only throwing a warning instead of aborting.
In my fix it will always choose the first enum value in this case.