Yes we do that all the time. Your code can check the debug interface first and only create USB client controller if debug interface is not USB. There are 2 ways, use mod pin to make serial or disable the debug interface (make it none)
How do i check for debug interface? - found it
edit: i don’t mind the error, ill just unload the app like before to reupload code, but the app does not run unless its switched to serial debug, that i have a problem with
So its either solder a DIP switch instead of a button or disable debug interface.
Not cool, that’s a breaking change for me.
There are no latching microswitches, and even the smallest SMD dip switches don’t fit in place of a microswitch 
I do not think you understand the change or we do not understand the problem. There is no breaking change!!
Is it correct? for App and UsbCDC to work you either have to switch to serial debugger (mod pin low) or disable debugger
In your designs you have a button for Mod pin, should i glue the button low when im done programming and when i give product to customer? (sarcasm)
Anyway… i think this way is better then it was before but i didn’t design for a simple DIP switch, yes i know i can solder a bit of wire when im done.
Again, nothing changed from before! Anyway, next release RC1 gives you more options. Rework debug interface API · Issue #971 · ghi-electronics/TinyCLR-Libraries · GitHub
RC1 you have an option to run in serial mode no need switching the mode pin.
Ok, thanks