The mutual-exclusivity check ran before the empty-element cleanup added
for bug 37075, so a bare -c (no value) left an empty string in
@letter_code, which the check saw as truthy and rejected even though
-c had effectively not been used. Move the cleanup above the check.
Also add the same mutual-exclusivity guard directly in
C4::Letters::SendQueuedMessages, since letter_code and
exclude_letter_code build the same search key and passing both would
otherwise let one silently clobber the other in the hashref passed to
->search - only the CLI script enforced this until now, so any other
caller could hit the silent-clobber bug.
Adds regression coverage: unit tests for the new exception in
SendQueuedMessages, and a script-level test reproducing the RM's
reported false positive.
Sponsored-by: OpenFifth <https://openfifth.co.uk/>
Signed-off-by: Pedro Amorim <pedro.amorim@openfifth.co.uk>
167622c08d