Fix issue where secondary rows were not being generated

src/reskit/soundtrack/engines/echo/dmf.rs

@@ -308,7 +308,8 @@ impl EchoFormat for DmfModule {
         // Iterate for each row, for each channel
         // Recall items are stored as self.channel_patterns[ channel ][ row_number ]
         let mut all_events: Vec<EchoEvent> = Vec::new();
-        for row_number in 0..self.rows_per_pattern {
+        let rows_per_pattern: u32 = self.channel_patterns[ 0 ].len() as u32;
+        for row_number in 0..rows_per_pattern {
             let events_this_row: Vec<EchoEvent> = get_events_for_row(
                 &mut channels,
                 &self.instruments,