Describe the bug

When attempting to make a processing pattern, nothing happens ingame and an error is logged.

How to reproduce the bug

In a pattern terminal, attempt to make a processing pattern. The one used here was for making iron from coal and raw iron.

When clicking the arrow, see the bug.

Expected behavior

The pattern should be made.

Additional details

I've selected Forge as the modloader below because Neoforge isn't an option. Same goes for 1.20 because there's no 1.20.6 option.

Which minecraft version are you using?

1.20

On which mod loaders does it happen?

Forge

Crash log

https://gist.github.com/MommyHeather/31f1a11c881929974fa5212fdc39c7e6

List.copyOf() is documented as "The given Collection must not be null, and it must not contain any null elements.". The debugger reveals that in the input is an ArrayList and slots that are not used (i.e. any slot other than the first two) seem to be null. Copying such an ArrayList with the function mentioned above will fail in EncodedProcessingPattern. So there are two possible causes: Either the processing pattern should not be an ArrayList or the copy has to be done in a different way.

Thanks for providing that lead @Mithi83. I've gone ahead and submitted a fix based on that information.

Wow, that was quick work. Your fix works here too.