null check on computed view cols, and IHasColumns interface

src/SqlSharpener/Model/Column.cs

@@ -216,7 +216,7 @@ from r in t.Value
 
         private void SetProperties(dac.TSqlObject tSqlObject)
         {
-            var sqlDataTypeName = tSqlObject.GetReferenced(dac.Column.DataType).ToList().First().Name.Parts.Last();
+            var sqlDataTypeName = tSqlObject.GetReferenced(dac.Column.DataType).ToList().FirstOrDefault()?.Name.Parts.Last();
             this.DataTypes = DataTypeHelper.Instance.GetMap(TypeFormat.SqlServerDbType, sqlDataTypeName);
             this.IsIdentity = dac.Column.IsIdentity.GetValue<bool>(tSqlObject);
             this.IsNullable = dac.Column.Nullable.GetValue<bool>(tSqlObject);

src/SqlSharpener/Model/IHasColumns.cs

@@ -0,0 +1,30 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace SqlSharpener.Model
+{
+    /// <summary>
+    /// Represents a table or view in the model.
+    /// </summary>
+    public interface IHasColumns
+    {
+        /// <summary>
+        /// Gets the name of the table or view.
+        /// </summary>
+        /// <value>
+        /// The name of the table or view.
+        /// </value>
+        string Name { get; }
+
+        /// <summary>
+        /// Gets the columns.
+        /// </summary>
+        /// <value>
+        /// The columns.
+        /// </value>
+        IEnumerable<Column> Columns { get; }
+    }
+}

src/SqlSharpener/Model/Table.cs

@@ -13,7 +13,7 @@ namespace SqlSharpener.Model
     /// Represents a table in the model.
     /// </summary>
     [Serializable]
-    public class Table
+    public class Table : IHasColumns
     {
         /// <summary>
         /// Initializes a new instance of the <see cref="Table"/> class.

src/SqlSharpener/Model/View.cs

@@ -12,7 +12,7 @@ namespace SqlSharpener.Model
     /// Represents a view in the model.
     /// </summary>
     [Serializable]
-    public class View
+    public class View : IHasColumns
     {
         /// <summary>
         /// Initializes a new instance of the <see cref="View"/> class.

src/SqlSharpener/SqlSharpener.csproj

@@ -78,6 +78,7 @@
     <Compile Include="DataType.cs" />
     <Compile Include="ForeignKeyConstraintVisitor.cs" />
     <Compile Include="Model\Column.cs" />
+    <Compile Include="Model\IHasColumns.cs" />
     <Compile Include="Model\RelationshipIdentifier.cs" />
     <Compile Include="Model\Table.cs" />
     <Compile Include="Model\View.cs" />