__main__ top-level script shadowing ImportError

[pyx]

Given main.py:

import nonexistent  # assuming this is... non-existent
from sanic import Sanic, response


app = Sanic(__name__)


@app.route('/')
async def index(request):
    return response.html('<p>Hello</p>')

When we try to import something non-existent, exception ImportError will be thrown,
line 38 of main.py does not preserve the exception, reporting preset message (what's provided on commandline) instead. This is what we will get:

python -m sanic main.app
No module named main found.
  Example File: project/sanic_server.py -> app
  Example Module: project.sanic_server.app

It is very hard to find the true cause if the import statement that failed is, let's say, buried three levels of modules deep, for example.