Avoid panic when pipe a variable to a custom command which have recursive call (#12491)

# Description
Fixes: #11351

And comment here is also fixed:
https://github.com/nushell/nushell/issues/11351#issuecomment-1996191537

The panic can happened if we pipe a variable to a custom command which
recursively called itself inside another block.

TBH, I think I figure out how it works to panic, but I'm not sure if
there is a potention issue if nushell don't mutate a block in such case.

# User-Facing Changes
Nan

# Tests + Formatting
Done

# After Submitting
Done

---------

Co-authored-by: Stefan Holderbach <sholderbach@users.noreply.github.com>

src/tests/test_parser.rs

@@ -1,4 +1,5 @@
 use crate::tests::{fail_test, run_test, run_test_with_env, TestResult};
+use nu_test_support::{nu, nu_repl_code};
 use std::collections::HashMap;
 
 use super::run_test_contains;
@@ -818,3 +819,41 @@ fn record_missing_value() -> TestResult {
 fn def_requires_body_closure() -> TestResult {
     fail_test("def a [] (echo 4)", "expected definition body closure")
 }
+
+#[test]
+fn not_panic_with_recursive_call() {
+    let result = nu!(nu_repl_code(&[
+        "def px [] { if true { 3 } else { px } }",
+        "let x = 1",
+        "$x | px",
+    ]));
+    assert_eq!(result.out, "3");
+
+    let result = nu!(nu_repl_code(&[
+        "def px [n=0] { let l = $in; if $n == 0 { return false } else { $l | px ($n - 1) } }",
+        "let x = 1",
+        "$x | px"
+    ]));
+    assert_eq!(result.out, "false");
+
+    let result = nu!(nu_repl_code(&[
+        "def px [n=0] { let l = $in; if $n == 0 { return false } else { $l | px ($n - 1) } }",
+        "let x = 1",
+        "def foo [] { $x }",
+        "foo | px"
+    ]));
+    assert_eq!(result.out, "false");
+
+    let result = nu!(nu_repl_code(&[
+        "def px [n=0] { let l = $in; if $n == 0 { return false } else { $l | px ($n - 1) } }",
+        "let x = 1",
+        "do {|| $x } | px"
+    ]));
+    assert_eq!(result.out, "false");
+
+    let result = nu!(
+        cwd: "tests/parsing/samples",
+        "nu recursive_func_with_alias.nu"
+    );
+    assert!(result.status.success());
+}