EDMIService: Improve logging, avoid confusion with import file methods

Service.EDMIService/IDB/Helpers.vb

@@ -76,19 +76,22 @@ Namespace IDB
 
         Public Function TestFileChecksumExists(pChecksum As String) As Long
             Try
+                Logger.Debug("Checking for Checksum [{0}]..", pChecksum)
+
                 Dim oChecksumSQL = $"SELECT IDB_OBJ_ID FROM TBIDB_FILE_OBJECT WHERE FILE_HASH = '{pChecksum}'"
                 Dim oExistingObjectId As Long = Database.GetScalarValue(oChecksumSQL)
 
                 If oExistingObjectId > 0 Then
-                    Logger.Info("Returning early with ObjectId [{0}] because Checksum [{1}] already exists.", oExistingObjectId, pChecksum)
+                    Logger.Info("Returning with ObjectId [{0}] because Checksum [{1}] already exists.", oExistingObjectId, pChecksum)
                     Return oExistingObjectId
                 End If
 
-                Return Nothing
+                Logger.Debug("Checksum does not exist.")
+                Return 0
 
             Catch ex As Exception
                 Logger.Error(ex)
-                Return Nothing
+                Return 0
 
             End Try
         End Function