Bugfix G0005

EPPlus/FormulaParsing/ExcelValues.cs

diff --git a/EPPlus/FormulaParsing/ExcelValues.cs b/EPPlus/FormulaParsing/ExcelValues.cs
index bcb75d5..57be38f 100644
--- a/EPPlus/FormulaParsing/ExcelValues.cs
+++ b/EPPlus/FormulaParsing/ExcelValues.cs
@@ -43,7 +43,12 @@
         /// <summary>
         /// Error error  // Google Bug G0004
         /// </summary>
-        Error
+        Error,
+        // Bug G0005
+        /// <summary>
+        /// ErrorValueIsNullOrEmpty error  // Google Bug G0005
+        /// </summary>
+        ErrorValueIsNullOrEmpty
     }
 
     /// <summary>
@@ -66,6 +71,7 @@
             public const string Ref = "#REF!";
             public const string Value = "#VALUE!";
             public const string Error = "#ERROR!";  // Bug G0004
+            public const string ErrorValueIsNullOrEmpty = "#ERRORVALUEISNULLOREMPTY!";  // Bug G0005
 
             private static Dictionary<string, eErrorType> _values = new Dictionary<string, eErrorType>()
                 {
@@ -77,6 +83,7 @@
                     {Ref, eErrorType.Ref},
                     {Value, eErrorType.Value},
                     {Error, eErrorType.Error},  // Bug G0004
+                    {ErrorValueIsNullOrEmpty, eErrorType.ErrorValueIsNullOrEmpty}  // Bug G0005
                 };
 
             /// <summary>
@@ -124,6 +131,11 @@
 
         internal static ExcelErrorValue Parse(string val)
         {
+            if (string.IsNullOrEmpty(val))  // Google Bug G0005
+            {
+                val = Values.ErrorValueIsNullOrEmpty;
+            }
+
             if (Values.StringIsErrorValue(val))
             {
                 return new ExcelErrorValue(Values.ToErrorType(val));
@@ -166,6 +178,8 @@
                     return Values.Value;
                 case eErrorType.Error:  // Bug G0004
                     return Values.Error;
+                case eErrorType.ErrorValueIsNullOrEmpty:  // Bug G0005
+                    return Values.ErrorValueIsNullOrEmpty;
                 default:
                     throw(new ArgumentException("Invalid errortype"));
             }