If we can't read the import, then we know we won't be able to import that module. But, still allow the file system to be checked for generated HTML.
If we can't read the import, then we know we won't be able to import
that module. But, still allow the file system to be checked for
generated HTML.

The reason this is necessary is when a module explicitly re-exports
a different module using __all__. The absolute import path doesn't
actually exist, so it is correct to read the HTML without being able
to import the module.

jswhit/pdoc,mindw/pdoc,BurntSushi/pdoc,somenxavier/pdoc,kchmck/pdoc,mayfield/pdoc