File Browser: revealing file fails when retyped before

[jri]

Try this:

1. Reveal an image file via File Browser
2. Retype it to Icon
3. Reveal the original file via File Browser again. This works. But note: from this moment on there are 2 Path topics with the same path in the DB.
4. Try revealing the original file a 3rd time. This results in a server side error due to ambiguous Path topics:

java.lang.RuntimeException: Creating file topic for repository path "/icons/CD.png" failed
    at de.deepamehta.plugins.files.FilesPlugin.createFileTopic(FilesPlugin.java:88)
    at de.deepamehta.plugins.files.FilesPlugin.createChildFileTopic(FilesPlugin.java:129)
    ...
Caused by: java.lang.RuntimeException: Fetching topic failed (key="dm4.files.path", value="/icons/CD.png")
    at de.deepamehta.core.impl.EmbeddedService.getTopic(EmbeddedService.java:107)
    at de.deepamehta.plugins.files.FilesPlugin.fetchFileTopic(FilesPlugin.java:365)
    at de.deepamehta.plugins.files.FilesPlugin.createFileTopic(FilesPlugin.java:78)
    ...
Caused by: java.util.NoSuchElementException: More than one element in org.neo4j.index.impl.lucene.LuceneIndex$1@7ae08787. First element is 'Node[3140]' and the second element is 'Node[3076]'
    at org.neo4j.helpers.collection.IteratorUtil.singleOrNull(IteratorUtil.java:118)
    ...

[jri]

Fixed in the course of #1044