Merge pull request #1462 from zed-industries/crash-on-goto-diagnostic

Fix two crashes related to diagnostics and bugs in mouse-based columnar selection

crates/gpui/src/text_layout.rs

@@ -238,8 +238,10 @@ impl Line {
         None
     }
 
-    // If round_to_closest, find the closest index to the given x position
-    // If !round_to_closest, find the largest index before the given x position
+    pub fn len(&self) -> usize {
+        self.layout.len
+    }
+
     pub fn index_for_x(&self, x: f32) -> Option<usize> {
         if x >= self.layout.width {
             None