Efficient script developing in Python

When making changes to larger modules, this is my current (inefficient) process:

1. Make needed change to code
2. Run program to test (using pdb - python3 -m pdb path/to/script.py
3. Program will throw an error
4. Fix error/create an exception
5. Run again
6. New error appears
7. Rinse an repeat

The data processing module I'm working on has many steps, and rerunning every time I make a code change to make sure there are no errors takes a long time and it's frustating. It's also obviously an inefficient way to develop a program, but I don't know what alternative

What advice do you have so that I don't have to run, and wait for, my whole data processing pipeline to find what the next error will be? Is there any way to make changes on the code and continue executing before the last error appeared? I'm a somewhat junior data person that haven't had formal CS/Software Engineering training.