Strange Lucene exception during reindex

Every time reindex is started, the following is printed to catalina.out at the beginning. Makes me wonder if everything is indexed or not.

SEVERE: Erroring indexing object. Class: class com.atlassian.confluence.spaces.SpaceDescription Content-id: 5
bucket.search.lucene.LuceneException: Calling property accessor method for attribute spaceKey threw an exception
at bucket.search.lucene.mapping.XmlLuceneDocumentFactory.getContentOfAttribute(XmlLuceneDocumentFactory.java:129)
at bucket.search.lucene.mapping.XmlLuceneDocumentFactory.createDocumentForObjectFromClassConfiguration(XmlLuceneDocumentFactory.java:46)
at bucket.search.lucene.mapping.XmlLuceneDocumentFactory.createDocument(XmlLuceneDocumentFactory.java:35)
at bucket.search.lucene.LuceneIndexer.getDocument(LuceneIndexer.java:156)
at bucket.search.lucene.LuceneIndexer.indexAll(LuceneIndexer.java:94)
at com.atlassian.confluence.search.lucene.ConfluenceIndexer.indexAll(ConfluenceIndexer.java:47)
at bucket.search.lucene.AbstractBatchIndexer.indexEntities(AbstractBatchIndexer.java:57)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at org.springframework.aop.framework.AopProxyUtils.invokeJoinpointUsingReflection(AopProxyUtils.java:61)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:149)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:116)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:56)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:138)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:152)
at $Proxy22.indexEntities(Unknown Source)
at com.atlassian.confluence.search.IndexingTask.run(IndexingTask.java:24)
at java.lang.Thread.run(Thread.java:534)
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.GeneratedMethodAccessor117.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at org.apache.commons.beanutils.PropertyUtils.getSimpleProperty(PropertyUtils.java:1185)
at org.apache.commons.beanutils.PropertyUtils.getNestedProperty(PropertyUtils.java:772)
at org.apache.commons.beanutils.PropertyUtils.getProperty(PropertyUtils.java:801)
at bucket.search.lucene.mapping.XmlLuceneDocumentFactory.getContentOfAttribute(XmlLuceneDocumentFactory.java:116)
... 19 more
Caused by: java.lang.NullPointerException
at com.atlassian.confluence.spaces.SpaceDescription.getSpaceKey(SpaceDescription.java:51)
... 26 more
Jan 5, 2005 1:46:06 PM bucket.search.lucene.LuceneIndexer indexAll