There’s no options to disable the lint checking. The errors and warnings are important as they point out issue with code which although it might work in Preview, it might not work in Live. The lint checking helps a lot.
The message that you are getting regarding the SITMember possibly being undefined is accurate - and it very might possibly be the case under certain circumstances.
Actually a better question would be “why is the code not flagged because it’s using both an await and .then()?” I’ll have to ask about that.