Error, "no module named" during set up of custom component

I am trying to create a custom_component, and can’t quite figure out why I can’t set it up.

I get the following error (UI setup):

Config flow could not be loaded: {"message":"Invalid handler specified"}

In the logs I see that it cannot find the validation_helpers module, but as you can see from the screenshot of the HA_config/custom_components/electricity_price directory, it’s right there.

Are there any weird limitations about importing local modules I’m unaware of? Otherwise, any idea what I’m doing wrong?