Credits window doesn't show

[GaLu]

There is no Credits window when I click Credits. Everything goes dark and new music theme starts. When I click right mouse button, or Esc + LMB everything comes back.

There is error in stdout.txt:

[WARN]TypeError: called object is not a function
    at /home/GaLu/caesaria/git/bin/resources/system/if_gui_widgets.js:204
    at /home/GaLu/caesaria/git/bin/resources/system/lobby.js:499
    at /home/GaLu/caesaria/git/bin/resources/system/lobby.js:361
    at -top- (native)