REPL preview causes unwanted side effects like deletion of unexpected objects

[ptomato]

Version

24.7.0

Platform

Linux hostname 6.14.11-300.fc42.x86_64 #1 SMP PREEMPT_DYNAMIC Tue Jun 10 16:24:16 UTC 2025 x86_64 GNU/Linux

Subsystem

No response

What steps will reproduce the bug?

• Start an interactive REPL session
• Type delete globalThis._ but don't press enter
• Backspace until the line is empty
• Type globalThis and press enter

How often does it reproduce? Is there a required condition?

Reliably reproducible. The REPL preview needs to be enabled; it does not reproduce with TERM=dumb. Not reproducible with 22.18.0.

What is the expected behavior? Why is that the expected behavior?

I would expect that the delete expression doesn't actually cause any deletion during evaluation for the preview. Failing that, I would expect that _ (which initially doesn't exist) would be deleted from the global scope.

What do you see instead?

> globalThis
Uncaught ReferenceError: globalThis is not defined

The globalThis object is actually deleted.

Additional information

No response