Errors when not using a Character Resource

[tyson-nw]

If I don't set a character resource, I start getting this error.

E 0:00:00:657   DialogueParser.gd:39 @ @data_setter(): Cannot open file 'res://Dialogue/Characters.tres'.
  <C++ Error>   Condition "err != OK" is true. Returning: Ref<Resource>()
  <C++ Source>  scene/resources/resource_format_text.cpp:1388 @ load()
  <Stack Trace> DialogueParser.gd:39 @ @data_setter()
                DialogueBox.gd:205 @ _enter_tree()
                dialog_player.gd:92 @ _ready()
E 0:00:00:657   DialogueParser.gd:39 @ @data_setter(): Failed loading resource: res://Dialogue/Characters.tres. Make sure resources have been imported by opening the project in the editor at least once.
  <C++ Error>   Condition "found" is true. Returning: Ref<Resource>()
  <C++ Source>  core/io/resource_loader.cpp:344 @ _load()
  <Stack Trace> DialogueParser.gd:39 @ @data_setter()
                DialogueBox.gd:205 @ _enter_tree()
                dialog_player.gd:92 @ _ready()
E 0:00:00:657   DialogueParser.gd:39 @ @data_setter(): Error loading resource: 'res://Dialogue/Characters.tres'.
  <C++ Error>   Condition "err != OK" is true. Returning: ret
  <C++ Source>  core/core_bind.cpp:76 @ load()
  <Stack Trace> DialogueParser.gd:39 @ @data_setter()
                DialogueBox.gd:205 @ _enter_tree()
                dialog_player.gd:92 @ _ready()

[nagidev]

Can you please share reproduction steps for this issue?