Symptoms

During the call ITableBlock::AddHSeparator() for an empty table, the following error is returned:

Arguments check failed. Expected: rowIdx >= 0

Cause

The exact cause of this issue is yet to be determined.

Resolution

The issue is currently under investigation.

As a workaround, you can use the repeating group as a table substitution.
You can refer to the following C# code snippets as an example:

IFieldDefinition groupTableDef = sectiondef.Fields.AddNew(FieldTypeEnum.FT_Group, "GroupTestTable");
groupTableDef.CanHaveRegion = true;

//Allow the groupTableDef to have instances
groupTableDef.IsRepeatable = true;

IFieldDefinition groupColNameDef = groupTableDef.Children.AddNew(FieldTypeEnum.FT_TextField, "ColumnName");
groupColNameDef.CanHaveRegion = true;
IFieldDefinition groupColSurnameDef = groupTableDef.Children.AddNew(FieldTypeEnum.FT_TextField, "ColumnSurname");
groupColSurnameDef.CanHaveRegion = true;

try
{
    Console.WriteLine($"Open document");
    IDocument doc = trainingbatch.Batch.Documents[0];
    doc.Open();
    try
    {
        Console.WriteLine($"Add table training");
        IPage docpage = doc.Pages[0];

        Console.WriteLine($"Find table");
        IField docsection = doc.Sections.FindByName("Document Section");

        for (int i = 0; i < 5; i++)
        {
            IField groupTable = FindField(doc.Sections, "Document Section\\GroupTestTable");
            groupTable.Instances.AddNew(i);

            IField Row = groupTable.Instances.Item(i);
            IField col1 = Row.Children.Item(0);
            IField col2 = Row.Children.Item(1);
            SetFieldRegion(engineTools.Engine, docpage, col1, TableLeft, TableTop + i * RowHeight, TableCenter, TableTop + (i+1) * RowHeight);
            SetFieldRegion(engineTools.Engine, docpage, col2, TableCenter, TableTop + i * RowHeight, TableRight, TableTop + (i+1) * RowHeight);

            int count = groupTable.Instances.Item(i).Children.Count;                        
        }   
    }           
}