Follow the GDScript style guide in every script

- Types on every parameter, return value and variable, and snake_case names
  (the player name limit is the constant MAX_NAME_LENGTH).
- Spelling fixes: *_triggered, character_selected, separator, caught_errors.
  The server's catched_errors key stays as the server sends it.
- Signals are connected with signal.connect() instead of by name.
- Code is ordered signals, constants, exported vars, vars, @onready vars,
  functions, with @onready on one line and two blank lines between functions.
- Every script starts with a ## description. Template comments, old LOC notes
  and commented-out code are gone, apart from the local play code.
- Lines are at most 100 characters, apart from the local play path.
- The screenshot tour turns off the blinking text cursor so pictures match.

SyncPopup.tscn

@@ -145,13 +145,13 @@ text = "SoundtracksRemoved"
 unique_name_in_owner = true
 layout_mode = 2
 
-[node name="CatchedErrorsVBox" type="VBoxContainer" parent="SyncPanel/ScrollContainer/SyncVBoxContainer" unique_id=63733711]
+[node name="CaughtErrorsVBox" type="VBoxContainer" parent="SyncPanel/ScrollContainer/SyncVBoxContainer" unique_id=63733711]
 unique_name_in_owner = true
 visible = false
 layout_mode = 2
 size_flags_horizontal = 3
 
-[node name="CatchedErrorsLabel" type="Label" parent="SyncPanel/ScrollContainer/SyncVBoxContainer/CatchedErrorsVBox" unique_id=1784389644]
+[node name="CaughtErrorsLabel" type="Label" parent="SyncPanel/ScrollContainer/SyncVBoxContainer/CaughtErrorsVBox" unique_id=1784389644]
 layout_mode = 2
 text = "CatchedErrors"
 horizontal_alignment = 1