fix upsert index of zero (#7350)

# Description

Try to fix #7347, this pr does not fix the error message to `upserting
beyond 1 + the list's length doesn't work,`, I feel this is still not
explicit or general engouh, if we want to change, what would be the best
message to be printed out ?

Add tests too

# User-Facing Changes

_(List of all changes that impact the user experience here. This helps
us keep track of breaking changes.)_

# Tests + Formatting

Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- [x] `cargo fmt --all -- --check` to check standard code formatting
(`cargo fmt --all` applies these changes)
- [x] `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used -A
clippy::needless_collect` to check that you're using the standard code
style
- [x] `cargo test --workspace` to check that all tests pass

# After Submitting

If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.

crates/nu-command/src/filters/upsert.rs

@@ -169,7 +169,7 @@ fn upsert(
                 if let Some(v) = input.next() {
                     pre_elems.push(v);
                 } else {
-                    return Err(ShellError::AccessBeyondEnd(idx - 1, *span));
+                    return Err(ShellError::AccessBeyondEnd(idx, *span));
                 }
             }
 

crates/nu-command/tests/commands/upsert.rs

@@ -87,3 +87,23 @@ fn uses_optional_index_argument_updating() {
 
     assert_eq!(actual.out, "[[a]; [8], [8]]");
 }
+
+#[test]
+fn index_does_not_exist() {
+    let actual = nu!(
+        cwd: ".", pipeline(
+        r#"[1,2,3] | upsert 4 4"#
+    ));
+
+    assert!(actual.err.contains("index too large (max: 3)"));
+}
+
+#[test]
+fn upsert_empty() {
+    let actual = nu!(
+        cwd: ".", pipeline(
+        r#"[] | upsert 1 1"#
+    ));
+
+    assert!(actual.err.contains("index too large (max: 0)"));
+}