Directory File Listing errors on received NAK

[0lionelzhang0]

Steps to reproduce:

• Turn off destination CFDP entity
• Make directory listing request
  indications = cfdp_directory_listing(remote_entity_id: 1, directory_name: ".", directory_file_name: "my_listing.txt")
• Wait a couple seconds
• Turn on destination CFDP entity
• See this error from the CFDP microservice

TypeError : no implicit conversion of nil into String
/tmp/d20250514-172-2v0pi/app/models/cfdp_mib.rb:241:in `join'
/tmp/d20250514-172-2v0pi/app/models/cfdp_mib.rb:241:in `get_source_file'
/tmp/d20250514-172-2v0pi/app/models/cfdp_source_transaction.rb:404:in `handle_nak'
/tmp/d20250514-172-2v0pi/app/models/cfdp_source_transaction.rb:387:in `handle_pdu'
/tmp/d20250514-172-2v0pi/app/models/cfdp_user.rb:77:in `block (2 levels) in start'
/usr/lib/ruby/gems/3.3.0/gems/openc3-6.4.0/lib/openc3/utilities/store_autoload.rb:184:in `block (3 levels) in read_topics'
/usr/lib/ruby/gems/3.3.0/gems/openc3-6.4.0/lib/openc3/utilities/store_autoload.rb:182:in `each'
/usr/lib/ruby/gems/3.3.0/gems/openc3-6.4.0/lib/openc3/utilities/store_autoload.rb:182:in `block (2 levels) in read_topics'
/usr/lib/ruby/gems/3.3.0/gems/openc3-6.4.0/lib/openc3/utilities/store_autoload.rb:181:in `each'
/usr/lib/ruby/gems/3.3.0/gems/openc3-6.4.0/lib/openc3/utilities/store_autoload.rb:181:in `block in read_topics'
/usr/lib/ruby/gems/3.3.0/gems/connection_pool-2.5.3/lib/connection_pool.rb:110:in `block (2 levels) in with'
/usr/lib/ruby/gems/3.3.0/gems/connection_pool-2.5.3/lib/connection_pool.rb:109:in `handle_interrupt'
/usr/lib/ruby/gems/3.3.0/gems/connection_pool-2.5.3/lib/connection_pool.rb:109:in `block in with'
/usr/lib/ruby/gems/3.3.0/gems/connection_pool-2.5.3/lib/connection_pool.rb:106:in `handle_interrupt'
/usr/lib/ruby/gems/3.3.0/gems/connection_pool-2.5.3/lib/connection_pool.rb:106:in `with'
/usr/lib/ruby/gems/3.3.0/gems/openc3-6.4.0/lib/openc3/utilities/store_autoload.rb:61:in `with'
/usr/lib/ruby/gems/3.3.0/gems/openc3-6.4.0/lib/openc3/utilities/store_autoload.rb:177:in `read_topics'
/usr/lib/ruby/gems/3.3.0/gems/openc3-6.4.0/lib/openc3/utilities/store_autoload.rb:89:in `public_send'
/usr/lib/ruby/gems/3.3.0/gems/openc3-6.4.0/lib/openc3/utilities/store_autoload.rb:89:in `method_missing'
/usr/lib/ruby/gems/3.3.0/gems/openc3-6.4.0/lib/openc3/topics/topic.rb:29:in `public_send'
/usr/lib/ruby/gems/3.3.0/gems/openc3-6.4.0/lib/openc3/topics/topic.rb:29:in `method_missing'
/tmp/d20250514-172-2v0pi/app/models/cfdp_user.rb:57:in `block in start'

CFDP plugin destination entity options

  OPTION destination_entity_id 1
  OPTION cmd_info CFDP CFDP_PDU PDU
  OPTION crcs_required false
  OPTION enable_eof_nak true
  OPTION default_transmission_mode ACKNOWLEDGED
  OPTION enable_keep_alive false
  OPTION ack_timer_interval 10
  OPTION ack_timer_expiration_limit 10
  OPTION nak_timer_interval 10
  OPTION nak_timer_expiration_limit 10

This is what my destination CFDP entity is logging (not COSMOS related)

Event: ENTERED_STATE, State: WAIT_FOR_EOF
Event: RECEIVED_EOF_NO_ERROR, State: WAIT_FOR_EOF
Send Ack EOF
Event: ENTERED_STATE, State: GET_MISSING_DATA
Send Nak

Things that work

• directory listing while destination CFDP entity is on (no NAKs sent)
• file uplink transaction when destination CFDP entity starts off (sends NAK)