Prevent Python from checking syntax errors inside an if statement whose condition isn't met

(I totally understand that return only makes sense inside functions.)

My question is: given that list in the following code is not None, is there a way to prevent Python from flagging the presence of return as a syntax error, and interrupting the execution?

list = [1,2,3]
if list is None: 
    return []
list = list + [4]

I'm asking this because I often run chunks of code inside a function to see what it does, step by step.

I don't mind the code execution being interrupted when the condition of the if statement is met, obviously.

But I wonder if there's a way to prevent python from checking syntax errors when they are inside an if statement whose condition is not met.