Better error handling using do (#5890)

* adds `capture-errors` flag for `do`

* adds `get-type` core command to get type

* fmt

* add tests in example

* fmt

* fix tests

* manually revert previous changes related to `get-type`

* adds method to check for error name using `into string`

* fix clippy

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

@@ -0,0 +1,13 @@
+use nu_test_support::{nu, pipeline};
+
+#[test]
+fn capture_errors_works() {
+    let actual = nu!(
+        cwd: ".", pipeline(
+        r#"
+        do -c {$env.use} | describe
+        "#
+    ));
+
+    assert_eq!(actual.out, "error");
+}

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

@@ -9,6 +9,7 @@ mod cp;
 mod date;
 mod def;
 mod default;
+mod do_;
 mod drop;
 mod each;
 mod echo;

crates/nu-command/tests/commands/str_/into_string.rs

@@ -171,3 +171,15 @@ fn from_nothing() {
 
     assert_eq!(actual.out, "");
 }
+
+#[test]
+fn from_error() {
+    let actual = nu!(
+        cwd: ".", pipeline(
+        r#"
+        do -c {$env.use} | into string
+        "#
+    ));
+
+    assert_eq!(actual.out, "nu::shell::name_not_found");
+}