UpdateSource is null on PrepareUpdates

[zam6ak]

Hi

I was following an example from NAppUpdate blog (which I now know is not only outdated but erroneous, see: http://pastebin.com/198EtE6B).

In it CheckForUpdates is passed IUpdateSource but unless set globally ahead of the time, it will cause the PrepareUpdates to fail.

So this does not work:

// prep
var updateManager = UpdateManager.Instance;
// more checks
updateManager.CheckForUpdates(updateSource); // passed in via method arg
// other stuff...
 updateManager.PrepareUpdates(); // <-- NPE

But this does

// prep
var updateManager = UpdateManager.Instance;
updateManager.UpdateSource = updateSource; // must set it here !!!
// more checks
updateManager.CheckForUpdates(updateSource);
// other stuff...
 updateManager.PrepareUpdates();  // <-- now it works....

Suggested fix:
in UpdateManager.cs inside of public void CheckForUpdates(IUpdateSource source) method after checking the args re-set UpdateSource to (maybe line 247)

UpdateSource = source;

so that subseqent call to Prepare does not fail...

Perhaps even better, do not allow methods to accept update source at all, and have checks in all methods to insure it is set before invoking them (unless there is a need to have varying update sources during update process ?)....