Code compiler sometimes causes some variables to be "unreference"

[FriskTheFallenHuman]

Has the title say while i was merging a modified obj_base_writter_draw_0 and compile the code entry and saved it, and launched the game i was immediately welcome with a unreferenced variable error, i checked the variable that the error gives and the variable is infact reference here's a code sniped of the code:

        var display_scale = (surface_get_width(application_surface) / __view_get(2, view_current))
        var finalx = (round(((letterx + offsetx) * display_scale)) / display_scale)
        var finaly = (round(((myy + offsety) * display_scale)) / display_scale)
        var scalex = (htextscale * halfscale)
        var scaley = (vtextscale * halfscale)

The variable in question is var display_scale = (surface_get_width(application_surface) / __view_get(2, view_current))

here's the full code entry: gml_Object_obj_base_writer_Draw_0

[Jacky720]

Can you post more context on the exact error message from the game?