Include MissingField Argument with Table.TransformColumnTypes Function for Power Query
From what I can see (and it's not listed in the M function reference) the built in Table.TransformColumnTypes doesn't accept the MissingField argument like most of the other Table functions. This is extremely troublesome because if you are processing a dynamic data source, columns could come and go. It would also seemingly be beneficial to potentially pull this into the Power Query UI and possibly even set this as the default.
The reason I suggest this is that In most scenarios that I come across, failing to transform a column type is not always something that is "mission critical". Especially when this is the default declarations that Power Query automatically inserts. (Perhaps default behavior for implementing this would be the automatically inserted declarations ignore missing fields and any explicit type changes after the fact do not ignore missing fields by default.
This suggested change would also help new users as there really isn't an easy way to catch individual columns with try/otherwise since it's actually multiple transformations.