Added TextIsValid logic to RequestTextFromFile function.

WetPancake/ProductServices.fs

@@ -44,7 +44,7 @@ module  Pancake =
             | :? InvalidOperationException -> return text
         }
 
-    let TextInFileIsValid filePath =
+    let TextInFileIsValidAsync filePath =
         async {
             return DataAccess.LoadFile filePath |> TextContainsValidEndToken
         }
@@ -153,7 +153,9 @@ module  Pancake =
                 GibberishLevelIsValid gibberishLevel |> ignore
                 SentencesIsValid sentences |> ignore
                 FilePathIsValid filePath |> ignore
-                // pattern match the TextInFileIsValid function
+                let! textIsValid = TextInFileIsValidAsync filePath
+                if textIsValid = true then ignore ()
+                else failwith @"The .txt file does not contain an end token ('.', '!' or '?')."
                 let data =
                     LoadFile filePath
                     |> ApplyStandardSetup
@@ -163,6 +165,7 @@ module  Pancake =
             with
             | :? ArgumentException as ex -> return ex.Message
             | :? FileNotFoundException as ex -> return ex.Message
+            | :? SystemException as ex -> return ex.Message
         }
 
     /// <summary>