find and handle more warning patterns

[jwillinghalpern]

Currently it only checks for "already exists." in the message fields and makes it a warning then. There are probably other cases that should do warning highlight. E.g. if an external data source is automatically added by pastring in script steps.

[jwillinghalpern]

since this is more of an ongoing whack-a-mole issue, i'm closing until warnings are encountered organically