Describe the bug

The presence of a PROMPT_COMMAND environment variable is prone to causing errors when feeding a tape into VHS.

This is common when using tool like mise, zoxide and/or custom prompt commands. For example my PROMPT_COMMAND includes _mise_hook;__zoxide_hook;generate_prompt; - all of these commands are bash functions, so they are not accessible from a VHS session that didn't source my bashrc.

Setup

• GNU bash, version 5.3.3
• macOS 15.6

To Reproduce

On my machine:

go run . ./examples/commands/enter.tape 

This reproducer should work on any machine:

PROMPT_COMMAND=does-not-exist go run . ./examples/commands/enter.tape 

Expected behavior

PROMPT_COMMAND= go run . ./examples/commands/enter.tape 

Additional context

Proposed fix: #692