Allow aliases to expand and ignore painting outside of lines (#3492)

crates/nu-engine/src/from_value.rs

@@ -374,6 +374,10 @@ impl FromValue for Vec<Value> {
                 value: UntaggedValue::Table(t),
                 ..
             } => Ok(t.clone()),
+            Value {
+                value: UntaggedValue::Row(_),
+                ..
+            } => Ok(vec![v.clone()]),
             Value { tag, .. } => Err(ShellError::labeled_error(
                 "Can't convert to table",
                 "can't convert to table",

crates/nu-engine/src/shell/painter.rs

@@ -46,9 +46,11 @@ impl Painter {
 
     fn paint(&mut self, styled_span: &Spanned<Style>) {
         for pos in styled_span.span.start()..styled_span.span.end() {
+            if pos < self.styles.len() {
                 self.styles[pos] = styled_span.item;
             }
         }
+    }
 
     fn into_string(self) -> String {
         let mut idx_start = 0;

tests/shell/pipeline/commands/internal.rs

@@ -306,6 +306,18 @@ fn run_custom_command_with_empty_rest() {
     assert_eq!(actual.err, r#""#);
 }
 
+#[test]
+fn alias_a_load_env() {
+    let actual = nu!(
+        cwd: ".",
+        r#"
+            def activate-helper [] { [[name, value]; [BOB, SAM]] }; alias activate = load-env (activate-helper); activate; $nu.env.BOB
+        "#
+    );
+
+    assert_eq!(actual.out, r#"SAM"#);
+}
+
 #[test]
 fn let_variable() {
     let actual = nu!(