I realized that the dialog that shows error messages at the end of the source-based installation routine does not work properly. The script code that I am referring to can be found at
https://github.com/retropie/RetroPie-Setup/blob/master/scriptmodules/retropiesetup.shinc#L528.
Every installation routine can add a text message to the global variable __ERRMSGS
. This variable is checked for any content at the end of all installation routines and displayed. This worked in the past, but for some reasons this functionality got broken somehow recently.
This error dialog helped a lot for judging the success of a re-compilation of the components.
Maybe someone from the community finds the bug?