Cannot choose subdirectory for directory name

[lylejantzi3rd]

For the option

? Specify a directory name where the source code of the generated components will be.
 If the directory does not exist in the current project structure it will be created.
 (app)

It would be nice to be able to specify a relative sub-directory, like client/src. When I try to use that, I get

>> Alphanumeric value is acceptable only.