Null responses from applications are not treated as errors in Flow by default, and I understand the reasoning for that. There are many cases where a null response is perfectly acceptable and not indicative of an error.
However, there are many instances where a null response shouldn't happen and is a problem.
I'm finding many cases where a Flow action (both for Zoho apps and non-Zoho apps) has some kind of glitch for some unknown reason, and the resulting response is null when it should never be. This is actually a failure, but isn't recorded as such.
This presents a problem, because the null responses creates errors downstream. This makes it impossible to restart a Flow in the correct place, because it thinks the error happened further downstream than it really did.
There should be a universal option on actions to make a null response register as an error.