NullReferenceException on VS2017 15.6.0

[MarkSky]

Viasfora version: 3.8.157
VS 2017 Community version: 15.6.0

After updating VS2017 version to 15.6.0, when I typed in SCSS file, I got erros:

<entry>
    <record>2058</record>
    <time>2018/03/07 08:19:41.231</time>
    <type>Error</type>
    <source>Editor or Editor Extension</source>
    <description>System.NullReferenceException: &#x4E26;&#x672A;&#x5C07;&#x7269;&#x4EF6;&#x53C3;&#x8003;&#x8A2D;&#x5B9A;&#x70BA;&#x7269;&#x4EF6;&#x7684;&#x57F7;&#x884C;&#x500B;&#x9AD4;&#x3002;&#x000D;&#x000A;   &#x65BC; Winterdom.Viasfora.Util.ToolTipWindow.TipTextViewModel.GetNearestPointInVisualSnapshot(SnapshotPoint editBufferPoint, ITextSnapshot targetVisualSnapshot, PointTrackingMode trackingMode)&#x000D;&#x000A;   &#x65BC; Microsoft.VisualStudio.Text.Editor.Implementation.WpfTextView.DoCompleteLayout(SnapshotPoint anchorPosition, Double verticalDistance, ViewRelativePosition relativeTo, Double effectiveViewportHeight, Double&amp; referenceLine, Double&amp; distanceAboveReferenceLine, Double&amp; distanceBelowReferenceLine, Nullable`1 cancel)&#x000D;&#x000A;   &#x65BC; Microsoft.VisualStudio.Text.Editor.Implementation.WpfTextView.InnerPerformLayout(SnapshotPoint anchorPosition, Double verticalDistance, ViewRelativePosition relativeTo, Double effectiveViewportWidth, Double effectiveViewportHeight, Boolean preserveViewportTop, Nullable`1 cancel)&#x000D;&#x000A;   &#x65BC; Microsoft.VisualStudio.Text.Editor.Implementation.WpfTextView.PerformLayout(ITextSnapshot newSnapshot, ITextSnapshot newVisualSnapshot, SnapshotPoint anchorPosition, Double verticalDistance, ViewRelativePosition relativeTo, Double effectiveViewportWidth, Double effectiveViewportHeight, Boolean preserveViewportTop, Nullable`1 cancel)&#x000D;&#x000A;   &#x65BC; Microsoft.VisualStudio.Text.Editor.Implementation.WpfTextView.PerformLayout(ITextSnapshot newSnapshot, ITextSnapshot newVisualSnapshot)&#x000D;&#x000A;   &#x65BC; Microsoft.VisualStudio.Text.Editor.Implementation.WpfTextView.AdvanceSnapshot(TextSnapshotChangedEventArgs e)&#x000D;&#x000A;   &#x65BC; Microsoft.VisualStudio.Text.Editor.Implementation.WpfTextView.AdvanceSnapshotOnUIThread(TextSnapshotChangedEventArgs e)&#x000D;&#x000A;   &#x65BC; Microsoft.VisualStudio.Text.Editor.Implementation.WpfTextView.OnVisualBufferChanged(Object sender, TextContentChangedEventArgs e)&#x000D;&#x000A;   &#x65BC; Microsoft.VisualStudio.Text.Utilities.GuardedOperations.RaiseEvent[TArgs](Object sender, EventHandler`1 eventHandlers, TArgs args)</description>
  </entry>
  <entry>
    <record>2059</record>
    <time>2018/03/07 08:19:41.240</time>
    <type>Error</type>
    <source>Editor or Editor Extension</source>
    <description>System.NullReferenceException: &#x4E26;&#x672A;&#x5C07;&#x7269;&#x4EF6;&#x53C3;&#x8003;&#x8A2D;&#x5B9A;&#x70BA;&#x7269;&#x4EF6;&#x7684;&#x57F7;&#x884C;&#x500B;&#x9AD4;&#x3002;&#x000D;&#x000A;   &#x65BC; Winterdom.Viasfora.Util.ToolTipWindow.TipTextViewModel.GetNearestPointInVisualSnapshot(SnapshotPoint editBufferPoint, ITextSnapshot targetVisualSnapshot, PointTrackingMode trackingMode)&#x000D;&#x000A;   &#x65BC; Microsoft.VisualStudio.Text.Editor.Implementation.WpfTextView.OnClassificationChanged(Object sender, ClassificationChangedEventArgs e)&#x000D;&#x000A;   &#x65BC; Microsoft.VisualStudio.Text.Classification.Implementation.ClassifierAggregator.OnBatchedTagsChanged(Object sender, BatchedTagsChangedEventArgs e)&#x000D;&#x000A;   &#x65BC; Microsoft.VisualStudio.Text.Utilities.GuardedOperations.RaiseEvent[TArgs](Object sender, EventHandler`1 eventHandlers, TArgs args)</description>
  </entry>

[tomasr]

Thanks for reporting, I'll try to take a look tonight!

[tomasr]

I haven't been able to reproduce this yet. It only happened for me the first time I launched VS, and now I can't seem to trigger it while under the debugger.

However, I did notice that the rainbow tooltip doesn't get properly updated. After it appears once (correctly), putting the mouse on top of a different brace causes the same (and now wrong) tooltip window to appear.

So far, I've tracked this to the IQuickInfoSession.Dismissed event not firing at all under 15.6, so the tooltip window doesn't get properly destroyed.

[tomasr]

I've added a workaround for the IQuickInfoSession.Dismissed issue. I have not been able to fully reproduce the original exception, but I suspect both are related.

Can either of your @MarkSky or @fdncred try the latest developer build and let me know if you still see the NullReferenceException happening?

[fdncred]

@tomasr Sure, I'll install it but where do I find the latest developer build?

[tomasr]

Sorry, @fdncred, you can find them here: https://ci.appveyor.com/project/tomasr/viasfora/build/artifacts

[fdncred]

@tomasr, Got it and installed it. So far, so good. I'll let you know if it pukes.

[fdncred]

@tomasr, I've seen the error twice now and both time it happened upon closing a solution. This is the latest error from my activity log.

System.NullReferenceException: Object reference not set to an instance of an  object. at
Winterdom.Viasfora.Util.ToolTipWindow.TipTextViewModel.GetNearestPointInVisualSnapshot(SnapshotPoint  editBufferPoint, ITextSnapshot targetVisualSnapshot, PointTrackingMode  trackingMode) at
Microsoft.VisualStudio.Text.Editor.Implementation.WpfTextView.OnClassificationChanged(Object  sender, ClassificationChangedEventArgs e) at
Microsoft.VisualStudio.Text.Classification.Implementation.ClassifierAggregator.OnBatchedTagsChanged(Object  sender, BatchedTagsChangedEventArgs e) at
Microsoft.VisualStudio.Text.Utilities.GuardedOperations.RaiseEvent[TArgs](Object  sender, EventHandler`1 eventHandlers, TArgs args)
--

[tomasr]

Thanks! I'll investigate further tonight. I presume the fact that something is getting stuck in memory, probably caused by IQuickInfoSession.Dismissed not getting fired, so the tooltip window is not getting cleaned up before the solution unloads. I'll see what I can do about it.

[tomasr]

OK, so made a few more changes which I think should fix that exception as well. Can you download the new build, @fdncred and give it another whirl? Thanks for all the help!

[fdncred]

@tomasr, installing now. Will let you know how it goes.

[tomasr]

Closing as I can't repro anymore. If it comes up again, feel free to add additional info as necessary and I'll reopen.