rename helper methods

src/datamatrix/encoder/default_placement.rs

@@ -164,7 +164,7 @@ impl DefaultPlacement {
             .codewords
             .chars()
             .nth(pos)
-            .ok_or(Exceptions::indexOutOfBoundsEmpty())? as u32;
+            .ok_or(Exceptions::indexOutOfBounds)? as u32;
         v &= 1 << (8 - bit);
         self.setBit(col as usize, row as usize, v != 0);