Cannot open waves with expanded attachment images

What steps will reproduce the problem?
1. Create new wave
2. Upload image attachment
3. Click the top right corner of the image to expand it
4. Reload page

What is the expected output?  What do you see instead?
Expected: wave reloads
Observed:
com.google.walkaround.wave.server.rpc.ClientExceptionHandler$ClientException: 
(java.lang.NullPointerException?) uri is null
    at com.google.gwt.core.client.impl.StackTraceCreator$CollectorEmulated.$fillInStackTrace(StackTraceCreator.java:162)
    at java.lang.Throwable.fillInStackTrace(Throwable.java:71)
    at java.lang.Exception.Exception(Exception.java:28)
    at java.lang.RuntimeException.RuntimeException(RuntimeException.java:28)
    at java.lang.NullPointerException.NullPointerException(NullPointerException.java:28)
    at com.google.gwt.safehtml.shared.SafeUriString.SafeUriString(SafeUriString.java:39)
    at com.google.gwt.user.client.ui.Image.$setUrl(Image.java:875)
    at org.waveprotocol.wave.client.doodad.attachment.render.ImageThumbnailWidget$DoubleBufferImage.$loadImage(ImageThumbnailWidget.java:502)
    at org.waveprotocol.wave.client.doodad.attachment.render.ImageThumbnailWidget.$setAttachmentUrl(ImageThumbnailWidget.java:568)
    at org.waveprotocol.wave.client.doodad.attachment.render.ImageThumbnailWidget.$setFullSizeMode(ImageThumbnailWidget.java:375)
    at org.waveprotocol.wave.client.doodad.attachment.render.ImageThumbnailRenderer.$onAttributeModified(ImageThumbnailRenderer.java:95)
    at org.waveprotocol.wave.client.doodad.attachment.render.ImageThumbnailRenderer.onAttributeModified(ImageThumbnailRenderer.java:95)
    at org.waveprotocol.wave.client.editor.RenderingMutationHandler$1.apply(RenderingMutationHandler.java:49)
    at org.waveprotocol.wave.client.common.util.JsoStringMap$1.apply(JsoStringMap.java:146)
    at org.waveprotocol.wave.client.common.util.JsoView.$each(JsoView.java:278)
    at org.waveprotocol.wave.client.common.util.JsoStringMap.$each(JsoStringMap.java:143)
    at org.waveprotocol.wave.client.common.util.JsoStringMap.each(JsoStringMap.java:143)
    at org.waveprotocol.wave.client.doodad.attachment.render.ImageThumbnailRenderer.onActivationStart(ImageThumbnailRenderer.java:79)
    at org.waveprotocol.wave.client.editor.gwt.GwtRenderingMutationHandler.onActivationStart(GwtRenderingMutationHandler.java:246)
    at org.waveprotocol.wave.client.editor.content.AgentAdapter.$setNodeMutationHandler(AgentAdapter.java:207)
    at org.waveprotocol.wave.client.editor.content.ContentDocument.$setupBehaviour(ContentDocument.java:323)
    at org.waveprotocol.wave.client.editor.content.ContentDocument.$setupBehaviour(ContentDocument.java:323)
    at org.waveprotocol.wave.client.editor.content.ContentDocument.$setupBehaviour(ContentDocument.java:323)
    at org.waveprotocol.wave.client.editor.content.ContentDocument.$setupBehaviour(ContentDocument.java:323)
    at org.waveprotocol.wave.client.editor.content.ContentDocument.$setInteractive(ContentDocument.java:1298)
    at org.waveprotocol.wave.client.wave.LazyContentDocument.$startRendering(LazyContentDocument.java:153)
    at org.waveprotocol.wave.client.wavepanel.render.BlipPager.pageIn(BlipPager.java:120)
    at org.waveprotocol.wave.client.wavepanel.render.PagingHandlerProxy.$pageIn(PagingHandlerProxy.java:41)
    at org.waveprotocol.wave.client.wavepanel.view.dom.full.BlipQueueRenderer.execute(BlipQueueRenderer.java:77)
    at org.waveprotocol.wave.client.scheduler.BrowserBackedScheduler.$workUnit(BrowserBackedScheduler.java:261)
    at org.waveprotocol.wave.client.scheduler.BrowserBackedScheduler.$workAll(BrowserBackedScheduler.java:314)
    at org.waveprotocol.wave.client.scheduler.BrowserBackedScheduler.$workSlice(BrowserBackedScheduler.java:346)
    at org.waveprotocol.wave.client.scheduler.BrowserBackedScheduler$1.$run(BrowserBackedScheduler.java:38)
    at org.waveprotocol.wave.client.scheduler.GwtSimpleTimer$2.run(GwtSimpleTimer.java:45)
    at com.google.gwt.user.client.Timer.fire(Timer.java:141)
    at UNKNOWN_CLASS.anonymous(UNKNOWN_FILE:0)
    at com.google.gwt.core.client.impl.Impl.apply(Impl.java:165)
    at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:196)
    at UNKNOWN_CLASS.anonymous(UNKNOWN_FILE:0)

I'll try putting a hack into WalkaroundAttachment.getAttachmentUrl() to make it 
never return null.

What browser and browser version are you using?  On what operating system?
Chrome on Linux

What URL does your browser show when the problem occurs?  Did you compile
walkaround on your machine, or are you using a public instance?
deployed from trunk

Please use labels and text to provide additional information.
Original issue reported on code.google.com by oh...@google.com on 13 Jan 2012 at 11:27
strikersix23 / walkaround

Cannot open waves with expanded attachment images #45
