Do you get a message when you do `Menu->Document->Line Wrapping which calls editor_set_line_wrapping()`?
Same Gtk-Warning only when **unsetting** the "Line Wrapping". That is the wrapping activation works Ok and shows no warning, clearing the active wrapping produces the warning.
Apparently, the warning is triggered by the Scintilla's message `SSM(sci, SCI_SETWRAPMODE, SC_WRAP_NONE, 0)`