fix: No error if no valid cert to sign mac app
fix: No error if no valid cert to sign mac app

Closes #897

MariaDima/electron-builder,electron-userland/electron-builder,ledinhphuong/electron-builder,electron-userland/electron-builder,mastergberry/electron-builder,loopline-systems/electron-builder,loopline-systems/electron-builder,mastergberry/electron-builder,develar/electron-builder,ledinhphuong/electron-builder,develar/electron-builder,badams/electron-builder,MariaDima/electron-builder,MariaDima/electron-builder,badams/electron-builder,ledinhphuong/electron-builder,badams/electron-builder,loopline-systems/electron-builder,badams/electron-builder,MariaDima/electron-builder,ledinhphuong/electron-builder,electron-userland/electron-builder,loopline-systems/electron-builder,MariaDima/electron-builder,mastergberry/electron-builder,mastergberry/electron-builder,develar/electron-builder,develar/electron-builder,ledinhphuong/electron-builder,MariaDima/electron-builder,ledinhphuong/electron-builder,loopline-systems/electron-builder