Very Tricky ADO.Net situation that does not throw an ERROR but should

Question

I have ADO.Net code as below, that calls a stored procedure. Within the stored procedure, I first get the result set through a SELECT query, and then after the SELECT statement call RAISERROR if the passed @companyId parameter value does not exist. I have run unit test on this code many times with a value of @companyId so RAISEERROR gets called, but I never see the call to ExecuteReader throw an error. Any reason why this strange counter-intuitive thing is happening?

sqlCmd = new SqlCommand("dbo.xyz_sp_Attributes_GetValues", new  SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["VHA_EDM_ConnectionString"].ConnectionString));
sqlCmd.CommandType = CommandType.StoredProcedure;
sqlCmd.Parameters.AddWithValue("@attributeId", attributeId);
sqlCmd.Parameters.AddWithValue("@companyId", companyId);
sqlCmd.Parameters.AddWithValue("@attributeScope", "Company");
sqlCmd.Connection.Open();
SqlDataReader dr = sqlCmd.ExecuteReader(CommandBehavior.CloseConnection);
while (dr.Read())
{
    attributeValue = dr["AttributeValue"].ToString();
}

The stored procedure code is something like below

SELECT col1, col2, ... where CompanyId = @companyId and AttributeId = @attributeId
if @companyId not exists (select companyId from Company where CompanyId = @companyId)
begin
 set @errMessage = N'Invalid Company Error'
 RAISERROR (@errMessage, 16, 1)
end

Answer 1

In this case there are more than one recordsets are returned. The first one is empty and that is why you don't get any error. You have to call the NextRecordset to get the error.

dr.NextResult(); // This will throw the error caused by RAISEERROR

It would be much easier to do the error checking in the client code instead of calling RAISEERROR which in any case will have to be handled as an Exception.

Catch a Sql Server RAISERROR at client side using SqlDataReader