Avoid NullRefereceExceptions when no document open

[mrlacey]

Fixes 56

Fixes #56

PR Type

What kind of change does this PR introduce?

• Bugfix

What is the current behavior?

Can get NREs

What is the new behavior?

Avoids these exceptions by adding suitable null checks.

PR Checklist

Please check if your PR fulfills the following requirements:

• Created a feature/dev branch in your fork (vs. submitting directly from a commit on main)
• Based off latest dev branch of XAML Studio
• Tested code with current supported SDKs
• Contains NO breaking changes to save/state files

Other information

[michael-hawker]

Thanks @mrlacey! Took me a second to realize what you meant issue, but I see now about clicking on the main navigation view items. You're actually not supposed to be able to click on them without a document loaded... 😅

Looks like in the change to #3 that I broke the logic for ViewModel.IsEditingDocument in the MainViewModel somehow which should disable those buttons:

XAMLStudio/XamlStudio/Views/MainPage.xaml

Lines 62 to 89 in 0cbcb00

	<muxc:NavigationViewItem x:Uid="MainPage_NavMenu_DataSources"
	IsEnabled="{x:Bind ViewModel.IsEditingDocument, Mode=OneWay}"
	Tag="DATASOURCES">
	<muxc:NavigationViewItem.Icon>
	<lcontrols:AppFontIcon IconName="Wheel" />
	</muxc:NavigationViewItem.Icon>
	</muxc:NavigationViewItem>
	<muxc:NavigationViewItem x:Uid="MainPage_NavMenu_Debug"
	IsEnabled="{x:Bind ViewModel.IsEditingDocument, Mode=OneWay}"
	Tag="DEBUG">
	<muxc:NavigationViewItem.Icon>
	<lcontrols:AppFontIcon IconName="Bug" />
	</muxc:NavigationViewItem.Icon>
	</muxc:NavigationViewItem>
	<muxc:NavigationViewItem x:Uid="MainPage_NavMenu_Properties"
	IsEnabled="{x:Bind ViewModel.IsEditingDocument, Mode=OneWay}"
	Tag="PROPERTIES">
	<muxc:NavigationViewItem.Icon>
	<lcontrols:AppFontIcon IconName="Properties" />
	</muxc:NavigationViewItem.Icon>
	</muxc:NavigationViewItem>
	<muxc:NavigationViewItem x:Uid="MainPage_NavMenu_Toolbox"
	IsEnabled="{x:Bind ViewModel.IsEditingDocument, Mode=OneWay}"
	Tag="TOOLBOX">
	<muxc:NavigationViewItem.Icon>
	<lcontrols:AppFontIcon IconName="Work" />
	</muxc:NavigationViewItem.Icon>
	</muxc:NavigationViewItem>

I see, it used to be that they were defined based on if the Welcome/Settings activity was open:

XAMLStudio/XamlStudio/Models/WorkspaceWindow.cs

Line 25 in 0cbcb00

public bool IsEditingDocument => OpenActivity != "SETTINGS" && OpenActivity != "WELCOME";

The problem is you can still click on "Explorer", but then from there get to any of the others... 🤔

I think this can be fixed by ensuring the ActiveFile is set as part of this condition instead or that OpenFiles count is not zero.

Let me know your thoughts!

[mrlacey]

If you can style them so it's clear they're not enabled then maybe do that. But then I'd wonder why they weren't enabled. I was having a poke around because I hadn't used it in a long time. I proposed a quick fix for an issue that is clearly something you're very unlikely to do once familiar with the app you are unlikely to try and do anything without a document open.

If I was you, I'd take this fix (it's rarely bad to add extra null checking) and then address what should be enabled (& when) as part of looking at improving the OOBE experience