Add lang_error to metadata tests

Author: HCastano

crates/metadata/Cargo.toml

@@ -34,6 +34,7 @@ default = [
 ]
 std = [
     "ink_prelude/std",
+    "ink_primitives/std",
     "serde/std",
     "scale-info/std",
 ]

crates/metadata/src/tests.rs

@@ -112,6 +112,12 @@ fn spec_contract_json() {
                 .done(),
         ])
         .events(Vec::new())
+        .lang_error(TypeSpec::with_name_segs::<ink_primitives::LangError, _>(
+            ::core::iter::Iterator::map(
+                ::core::iter::IntoIterator::into_iter(["ink", "LangError"]),
+                ::core::convert::AsRef::as_ref,
+            ),
+        ))
         .done();
 
     let mut registry = Registry::new();
@@ -168,6 +174,13 @@ fn spec_contract_json() {
             ],
             "docs": [],
             "events": [],
+            "lang_error": {
+              "displayName": [
+                "ink",
+                "LangError"
+              ],
+              "type": 3
+            },
             "messages": [
                 {
                     "args": [