Add column from Freebase raises exception

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What steps will reproduce the problem?
1. Import the attached project (two rows, two columns)
2. Click on the "Freebase ID" menu and select "Edit Column" > "Add Columns From 
Freebase...
3. Specify the new column as /imdb/topic/title_id and press OK

What is the expected output? What do you see instead?

In the UI, the status monitor indicates 100% completion but never actually 
completes.  It can be cancelled.

On the server console window, the following appears:

java.lang.NullPointerException at 
com.google.gridworks.model.changes.DataExtensionChange.save(DataExtensionChange.
java:264)
        at com.google.gridworks.history.History.writeOneChange(History.java:74)
        at com.google.gridworks.history.History.writeOneChange(History.java:67)
        at com.google.gridworks.history.History.writeOneChange(History.java:56)
        at com.google.gridworks.io.FileHistoryEntryManager.saveChange(FileHistoryEntryManager.java:81)
        at com.google.gridworks.io.FileHistoryEntryManager.saveChange(FileHistoryEntryManager.java:70)
        at com.google.gridworks.history.HistoryEntry.apply(HistoryEntry.java:100)
        at com.google.gridworks.history.History.addEntry(History.java:98)
        at com.google.gridworks.operations.column.ExtendDataOperation$ExtendDataProcess.run(ExtendDataOperation.java:270)
        at java.lang.Thread.run(Unknown Source)
Exception in thread "Thread-39" java.lang.RuntimeException: Failed to apply 
change
        at com.google.gridworks.history.HistoryEntry.apply(HistoryEntry.java:106)
        at com.google.gridworks.history.History.addEntry(History.java:98)
        at com.google.gridworks.operations.column.ExtendDataOperation$ExtendDataProcess.run(ExtendDataOperation.java:270)
        at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.NullPointerException
        at com.google.gridworks.model.changes.DataExtensionChange.save(DataExtensionChange.java:264)
        at com.google.gridworks.history.History.writeOneChange(History.java:74)
        at com.google.gridworks.history.History.writeOneChange(History.java:67)
        at com.google.gridworks.history.History.writeOneChange(History.java:56)
        at com.google.gridworks.io.FileHistoryEntryManager.saveChange(FileHistoryEntryManager.java:81)
        at com.google.gridworks.io.FileHistoryEntryManager.saveChange(FileHistoryEntryManager.java:70)
        at com.google.gridworks.history.HistoryEntry.apply(HistoryEntry.java:100
)
        ... 3 more

What version of the product are you using? On what operating system?

Trunk, Windows 7 

Please provide any additional information below.

Although it's presumably unusual to have two keys in the /en namespace that map 
to the same topic, I don't think that's what's causing it.  There are other 
cases where this exception occurs; this was just the simplest one I could 
identify.

I have no idea what's causing this or what a workaround might be.

Original issue reported on code.google.com by bil...@gmail.com on 10 Sep 2010 at 1:45

Attachments:

• test.gridworks.tar.gz

[GoogleCodeExporter]

Fixed by r1261.

Original comment by dfhu...@google.com on 10 Sep 2010 at 5:05

• Changed state: Fixed

[GoogleCodeExporter]

Original comment by tfmorris on 18 Sep 2012 at 2:58

• Added labels: Milestone-2.0