I haven't seen this before - in a fresh project Behavior Designer will build without a problem. Maybe you referenced the Behavior Designer editor from an Assembly Definition?
I looked at my asmdefs, and there is one that is referencing the Behavior Designer asmdef, but none of them are referencing the Behavior Designer Editor dll
None of the Behavior Designer runtime code references any editor code so it's something unique in your project. In a fresh project with Behavior Designer it will build without a problem.
You could narrow this down by removing assets until you have a working build. Make sure you have a backup before you do this.