Attempted fix for DBnull error on printing by comparing number of actual downloaded vouchers to DeliveredQuantity

BulkPrinting/BulkPrinting/BatchForm.Designer.cs

         private void InitializeComponent()
         {
             this.components = new System.ComponentModel.Container();
-            System.Windows.Forms.DataGridViewCellStyle dataGridViewCellStyle2 = new System.Windows.Forms.DataGridViewCellStyle();
+            System.Windows.Forms.DataGridViewCellStyle dataGridViewCellStyle1 = new System.Windows.Forms.DataGridViewCellStyle();
             System.ComponentModel.ComponentResourceManager resources = new System.ComponentModel.ComponentResourceManager(typeof(BatchForm));
             this.contextMenuStrip1 = new System.Windows.Forms.ContextMenuStrip(this.components);
             this.pnlSplitGrids = new System.Windows.Forms.Panel();
             this.dgvBatches.AllowUserToAddRows = false;
             this.dgvBatches.AllowUserToDeleteRows = false;
             this.dgvBatches.AllowUserToResizeRows = false;
-            dataGridViewCellStyle2.BackColor = System.Drawing.Color.Azure;
-            this.dgvBatches.AlternatingRowsDefaultCellStyle = dataGridViewCellStyle2;
+            dataGridViewCellStyle1.BackColor = System.Drawing.Color.Azure;
+            this.dgvBatches.AlternatingRowsDefaultCellStyle = dataGridViewCellStyle1;
             this.dgvBatches.Anchor = ((System.Windows.Forms.AnchorStyles)((((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Bottom) 
             | System.Windows.Forms.AnchorStyles.Left) 
             | System.Windows.Forms.AnchorStyles.Right)));

BulkPrinting/BulkPrinting/BatchForm.cs

                 MessageBox.Show("A print dialog is already open for this batch","Cannot open print dialog",MessageBoxButtons.OK,MessageBoxIcon.Exclamation);
                 return;
             }
+
+            int DeliveredVoucherCount = (int)dgvBatches.SelectedRows[0].Cells[dgvBatches.Columns["DeliveredQuantity"].Index].Value;
+            string Sql = "SELECT COUNT(*) FROM Voucher WHERE BatchId=@id";
+            SQLiteCommand Command = new SQLiteCommand(Sql, Globals.DBConnection);
+            Command.Parameters.Add(new SQLiteParameter("@id", BatchID));
+            int DownloadedVoucherCount = Convert.ToInt32(Command.ExecuteScalar());
+            if (DownloadedVoucherCount < DeliveredVoucherCount) {
+                MessageBox.Show(string.Format("Batch {0} has not finished downloading.\nDownloaded {1} of {2} vouchers in batch.",BatchID,DownloadedVoucherCount,DeliveredVoucherCount), "Cannot open print dialog", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
+                return;
+            }
+
+
             this.BeginInvoke((Action)delegate {
                 PrintForm PrintFormInstance = new PrintForm();
                 Globals.OpenBatches.Add(BatchID);