bug#25194: 25.1; Python debugger breakpoint error

[Eli Zaretskii]

> From: Live System User <nyc4bos@aol.com>
> Date: Tue, 13 Dec 2016 05:10:03 -0500
> 
> 4. Cick on "Set Breakpoint"
> 
>    I now get the error:
>    
>       Wrong type argument: stringp, nil
> 
>    Turning on `debug-on-error' yields the same results.
>    However, on the *Messages* buffer there is a little more
>    information about the error:
> 
>        gud-format-command: Wrong type argument: stringp, nil
> 
>    How does one debug this problem further?

Did you try debug-on-entry?