Pipelines with each and null at the end break

[KAAtheWiseGit]

Describe the bug

If a pipeline with an each closure, which uses the $in argument (either explicitly or implicitly, like $list | each { command }) has a null` at the end, it doesn't work.

How to reproduce

-> [a] | each { cp $in b } | null
# `a` will not be copied

Expected behavior

null not impacting the command semantics.

Screenshots

No response

Configuration

key	value
version	0.92.0
branch
commit_hash
build_os	linux-x86_64
build_target	x86_64-alpine-linux-musl
rust_version	rustc 1.77.0 (aedd173a2 2024-03-17) (Alpine Linux 1.77.0-r0)
cargo_version	cargo 1.77.0
build_time	2024-04-03 10:33:03 +00:00
build_rust_channel	release
allocator	mimalloc
features	default, sqlite, trash, which
installed_plugins

Additional context

No response