Validation and stuff

MultiTool.Shared/IDictionaryEx.vb

@@ -4,6 +4,11 @@ Module IDictionaryEx
     <Extension()>
     Function GetOrDefault(Of TKey, TValue)(pDictionary As Dictionary(Of TKey, TValue), pKey As TKey, Optional pOnMissing As TValue = Nothing) As TValue
         Dim oValue As TValue
+
+        If pKey Is Nothing Then
+            Return Nothing
+        End If
+
         Return IIf(pDictionary.TryGetValue(pKey, oValue), oValue, pOnMissing)
     End Function