I would like to have an array formula that returns the order# contained in
column A if column B has an error in it. Is it also possible to enter this
formula into one cell as I don't know how many errors could be in column B.

Example

A B
123456 S-12-04
123457 #N/A
123458 DS-12-06
123459 #N/A
123460 S-12-05

Array formula would return.... 123457, 123459

Thanks in advance