Best way to deal with a typical exception to the premise?

Question

Which of the following ways to work with this precondition is more desirable and what are the more important consequences?

1:

If Not Exists(File) Then 
    ThrowException
    Exit
End If
File.Open
...work on file...

2:

If Exists(File) Then 
    File.Open 
    ....work on file...
Else
    ThrowException
    Exit
End 

Note. Checking for a file is just an example of a HANDLE prerequisite. Clearly, there is a good argument for checking for files themselves throwing their own exceptions up.

Answer 1

I prefer the first option, so the best documents are that there are preconditions

Answer 2

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