You should be able to save a flow even if it has an error

[copro]

Sometimes in a very complicated flow you don't want to lose your work just because there is an error that you cannot figure out at the moment!

[index]

strongly agree with this.

[GeekyMom]

Yes, I agree.  It could save with a note that there is an error - similar to what you see if the flow is turned off. 

[KarenTA]

Yes, it's very frustrating that it doesn't save when you hit a brick wall. You may need to save where you are and return to it later.