From c9aa6ba0f33e76852f94eb993ad5c4798379bf0f Mon Sep 17 00:00:00 2001
From: Andrej Kolchin <KAAtheWise@protonmail.com>
Date: Mon, 4 Dec 2023 18:49:36 +0000
Subject: [PATCH] Add special error for calling `metadata` on $env and $nu
 (#11228)
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Trying to call `metadata $env` or `metadata $nu` will throw an error:

```Nushell
~> metadata $nu
Error:   × Built-in variables `$env` and `$nu` have no metadata
   ╭─[entry #1:1:1]
 1 │ metadata $nu
   ·          ─┬─
   ·           ╰── no metadata available
   ╰────
```
---
 crates/nu-protocol/src/engine/stack.rs | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/crates/nu-protocol/src/engine/stack.rs b/crates/nu-protocol/src/engine/stack.rs
index c6c71b5f0..161cd92a1 100644
--- a/crates/nu-protocol/src/engine/stack.rs
+++ b/crates/nu-protocol/src/engine/stack.rs
@@ -3,6 +3,7 @@ use std::collections::{HashMap, HashSet};
 use crate::engine::EngineState;
 use crate::engine::DEFAULT_OVERLAY_NAME;
 use crate::{ShellError, Span, Value, VarId};
+use crate::{ENV_VARIABLE_ID, NU_VARIABLE_ID};
 
 /// Environment variables per overlay
 pub type EnvVars = HashMap<String, HashMap<String, Value>>;
@@ -80,6 +81,16 @@ impl Stack {
             }
         }
 
+        if var_id == NU_VARIABLE_ID || var_id == ENV_VARIABLE_ID {
+            return Err(ShellError::GenericError(
+                "Built-in variables `$env` and `$nu` have no metadata".into(),
+                "no metadata available".into(),
+                Some(span),
+                None,
+                Vec::new(),
+            ));
+        }
+
         Err(ShellError::VariableNotFoundAtRuntime { span })
     }