Eat exception or check null?

Question

I have the following code:

private async Task <string>IsolatedStorageReadTextFile(string uFileName)
{
        string sRet = "";

        StorageFile file = await ApplicationData.Current.LocalFolder.GetFileAsync(uFileName);
        if (file != null)
        {
            using (var inputStream = await file.OpenReadAsync())
            using (var classicStream = inputStream.AsStreamForRead())
            using (var streamReader = new StreamReader(classicStream))
            {
                while (streamReader.Peek() >= 0)
                {
                    sRet = streamReader.ReadLine();
                }
            }
        }
        return sRet;
}

When the file in question doesn't exist, the IDE throws an error:

Should I

1) let the IDE debug warner ignore this error (say "Don't break on this exception"), and I should just let "if (file != null)" do the job

2) or should I check if the file actually exists

3) use try-catch?

I had to add an important part of code according to the answers:

    private async Task <bool> LocalExists(string uFileName)
    {
        bool b = false;
        //https://stackoverflow.com/questions/8626018/how-to-check-if-file-exists-in-a-windows-store-app
        try
        {
            StorageFile file = await ApplicationData.Current.LocalFolder.GetFileAsync(uFileName);
            b = (file != null);
        }
        catch (Exception ex)
        {
            b = false;
        }

        return b;
    }

This throws the same exception since in UWP, there seems no other way of checking if a file actually exists than trying to access it:

How to check if file exists in a Windows Store App?

So the question remains.

Answer 1

You can either check the file exists before, or handle the exception.

When you don't catch the exception, the next line will not be executed so you can't check file for null (not like other programming language like C++).

The option, don't break on this option, only don't pause (activate a breakpoint) the application when exception is thrown only, doesn't change the behaviour of the program.