Match cleanup (#2294)

* Delete unnecessary match

* Use `unwrap_or_else()`

* Whitespace was trim on file save

* Use `map_or_else()`

* Use a default to group all match arms with same output

* Clippy made me do it

crates/nu-protocol/src/value.rs

@@ -52,11 +52,8 @@ impl UntaggedValue {
     /// Get the corresponding descriptors (column names) associated with this value
     pub fn data_descriptors(&self) -> Vec<String> {
         match self {
-            UntaggedValue::Primitive(_) => vec![],
             UntaggedValue::Row(columns) => columns.entries.keys().map(|x| x.to_string()).collect(),
-            UntaggedValue::Block(_) => vec![],
-            UntaggedValue::Table(_) => vec![],
-            UntaggedValue::Error(_) => vec![],
+            _ => vec![],
         }
     }