Selecting empty csv file throws an Exception

**System Information (please complete the following information):**
- (No idea where I can get Model builder version)
- Visual studio version is 17.11.0 Preview 7.0

**Describe the bug**
When I select Question Answer template, and then select empty file it throws an Exception

**To Reproduce**
Steps to reproduce the behavior:
Create Machine learning model
Select a Question Answering template (Local)
Press next step
Browse
Select an empty csv file

**Expected behavior**
I would expect some message that the file is empty.

**Error**
Unable to parse file. Only comma, tab or semi-colon delimited files are allowed.

at StreamJsonRpc.JsonRpc.d__154`1.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.ML.ModelBuilder.Actions.DataTextActions.d__14.MoveNext() in /_/src/Microsoft.ML.ModelBuilder/Actions/DataTextActions.cs:line 284
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.ML.ModelBuilder.Actions.DataTextActions.d__2.MoveNext() in /_/src/Microsoft.ML.ModelBuilder/Actions/DataTextActions.cs:line 61
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.ML.ModelBuilder.ToolWindows.DataTextViewModel.d__136.MoveNext() in /_/src/Microsoft.ML.ModelBuilder/ViewModels/DataTextViewModel.cs:line 683
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.ML.ModelBuilder.ToolWindows.TextDataControl.<b__3_0>d.MoveNext() in /_/src/Microsoft.ML.ModelBuilder/ToolWindows/DataTabComponents/TextDataControl.xaml.cs:line 69

**Screenshots**

Bắt đầu với Microsoft.ML.ModelBuilder/Actions/DataTextActions.cs quanh dòng 284 và theo dõi lệnh gọi đến ViewModels/DataTextViewModel.cs quanh dòng 683. Tái hiện luồng template Question Answering với một CSV rỗng, sau đó xác minh rằng hệ thống báo tệp rỗng thay vì phát sinh ngoại lệ dấu phân cách.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.