fix(commands): don't indent empty lines (#1653)

* fix(commands): don't indent empty lines

Fixes: https://github.com/helix-editor/helix/issues/1642

* Apply suggestions

* Update helix-term/src/commands.rs

* Update helix-term/src/commands.rs

Co-authored-by: Blaž Hrastnik <blaz@mxxn.io>

helix-term/src/commands.rs

@@ -4654,9 +4654,13 @@ fn indent(cx: &mut Context) {
 
     let transaction = Transaction::change(
         doc.text(),
-        lines.into_iter().map(|line| {
+        lines.into_iter().filter_map(|line| {
+            let is_blank = doc.text().line(line).chunks().all(|s| s.trim().is_empty());
+            if is_blank {
+                return None;
+            }
             let pos = doc.text().line_to_char(line);
-            (pos, pos, Some(indent.clone()))
+            Some((pos, pos, Some(indent.clone())))
         }),
     );
     doc.apply(&transaction, view.id);