Only preserve excerpts for invalid diagnostics if they contain cursors

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

crates/editor/src/editor.rs

@@ -3116,6 +3116,10 @@ impl Editor {
         .collect()
     }
 
+    pub fn local_anchor_selections(&self) -> &Arc<[Selection<Anchor>]> {
+        &self.selections
+    }
+
     fn resolve_selections<'a, D, I>(
         &self,
         selections: I,