Add assert to Row::grow

This enforces the invariant that Row::Grow is only called when the row
actually needs to be grown.

1 files changed, 3 insertions, 1 deletions

diff --git a/src/grid/row.rs b/src/grid/row.rs
index f7e4a98a..e907b61d 100644
--- a/src/grid/row.rs
+++ b/src/grid/row.rs
@@ -30,8 +30,10 @@ impl<T: Copy + Clone> Row<T> {
     }
 
     pub fn grow(&mut self, cols: Column, template: &T) {
+        assert!(self.len() < * cols);
+
         while self.len() != *cols {
-            self.push(*template);
+            self.inner.push(*template);
         }
     }