In `internal/uidriver/glfw/run_notsinglethread.go`, if the `UserInterface.init()` function returns an error, the `loop` is
executed regardless and the error is discarded. This behavior will hide the error returned by `init()` and might trigger
some crashes (see #1688).
A partial fix was implemented in 6c4edf8 , however that commit alone is not enough: the code now is correctly returning
the error via the `ch` channel, but it still executes the `loop()` function. This merge request skips `loop()` call if `init()`
had an error.
Updates #1688
3ef1d04935