Looking for some advice on need to check write to flash

Hello All

I am writing a custom bootstrap loader.  I am looking for potential failures and how to mitigate them in Verify Erase and Verify Write steps:

1. Erase Segment
2. Verify Erase (making sure all bits are high)
3. Write to erased segment
4. Verify Write

If Erase fails verification, what do you do? I try again, is that the right thing to do?

if write fails verification, what do you do? Should I try to erase and write again?

Thanks...