Handle error while creating checksum

Global_Indexer/ClassIndexFunctions.vb

@@ -10,12 +10,14 @@ Public Class ClassIndexFunctions
                 Filename = Filename.Replace("'", "''")
             End If
 
-            Try
-                oHash = FILESYSTEM.GetChecksum(Filename)
-            Catch ex As Exception
-                LOGGER.Error(ex)
-                oHash = ""
-            End Try
+            ' If file cannot be accessed, checksum cannot be generated
+            ' In this case, the file should be treated as not yet existing
+            oHash = FILESYSTEM.GetChecksum(Filename)
+
+            If oHash Is Nothing Then
+                LOGGER.Warn("Checksum for file {0} could not be generated. Treating as new file.", Filename)
+                Return Nothing
+            End If
 
             oSQL = "SELECT *  FROM TBGI_FILES_USER WHERE UPPER(FILE_HASH) = UPPER('" & oHash & "') AND WORKED = 0 ORDER BY ADDED_WHEN"
             Dim oResult As DataTable = ClassDatabase.Return_Datatable_CS(oSQL, MyConnectionString, True)