Improve Error handling across the board

MultiTool.Common/Documents/DocumentRow.vb

@@ -35,11 +35,11 @@ Namespace Documents
             End Get
         End Property
 
-        Public ReadOnly Property Errors As List(Of String)
+        Public ReadOnly Property Errors As List(Of FieldError)
             Get
                 Return Fields.
                     Where(Function(f) f.Value.HasError).
-                    Select(Function(f) $"{f.Key} has Error: {f.Value.Error}").ToList()
+                    SelectMany(Function(f) f.Value.Errors).ToList()
             End Get
         End Property
 
@@ -57,11 +57,8 @@ Namespace Documents
             Private _Original As String = ""
 
             Public Property DataType As ColumnType = ColumnType.String
-            Public Property [Error] As FieldError = FieldError.None
 
-            Public Sub New()
-
-            End Sub
+            Public Property Errors As New List(Of FieldError)
 
             Public Property Original As String
                 Get
@@ -107,9 +104,17 @@ Namespace Documents
                 End Select
             End Function
 
+            Public Sub AddFieldError(pType As FieldErrorType, pMessage As String)
+                Errors.Add(New FieldError() With {
+                    .Type = pType,
+                    .Message = pMessage
+                })
+            End Sub
+
             Public ReadOnly Property HasError As Boolean
                 Get
-                    Return [Error] <> FieldError.None Or (IsRequired And Final = String.Empty)
+                    ' Required check was moved to DocumentLoader
+                    Return Errors.Count > 0 'Or (IsRequired And Final = String.Empty)
                 End Get
             End Property