No value should be returned when R Source does not exisr
No value should be returned when R Source does not exisr

Fixes https://github.com/jasp-stats/jasp-test-release/issues/2003

jasp-stats/jasp-desktop,jasp-stats/jasp-desktop,jasp-stats/jasp-desktop,jasp-stats/jasp-desktop,jasp-stats/jasp-desktop,jasp-stats/jasp-desktop,jasp-stats/jasp-desktop,jasp-stats/jasp-desktop