No, parameters like `type` let the developer control what his users provides.  Violating that produces a runtime error, and exit.

But in general argparse does not try to control values that the developer uses.  There's plenty of time during development to catch error such as this - if they are errors at all.  

'type' does not 'declare' what the attribute will be.  It is a function that is applied to the input string, and converts that to something or other, or raises a TypeError.  It is used only if there is a string value to work on, either from the user, or a string default.  

This is not a bug, so should be closed.