Lisp exception when using value returned by status-line-get-box

[rigdern]

Repro steps

I reproed this with Boxer 3.4.19 2024-06-24

1. Download, unzip, and open status-line-get-box repro.box.zip
2. Execute the line get-char (it'll put a prompt in Boxer's status line)
3. Type the letter A and hit enter

Unexpected result: Trying to use the return value of status-line-get-box results in a Common Lisp exception:

Lisp Error:
  "A" fell through ETYPECASE expression inside BOXER:VIRTUAL-COPY.
  Wanted one of (BOXER:VIRTUAL-COPY BOXER::VIRTUAL-PORT BOXER::BOX NUMBER SYMBOL BOXER::FOREIGN-DATA). 

Screenshot of the repro file: