Warn if table in `tables` config is not found

[pnadolny13]

From my testing today it looks like we attempt to find a match but if not we silently complete with no records synced. As a user it would be nice to get a warning, or even an error potentially, if my configured table wasnt found. If I was running this is production and the table disappeared the job would continue to succeed as if the data was synced, which could lead to some unexpected results and might make me lean in favor of throwing an error.

[peter-malcolm-bw]

We just got burned by this issue too. This would be a great addition to the tap 👍