Version: 0.6.3 OS: Linux
Similar to an issue in OrientDB https://github.com/orientechnologies/orientdb/issues/9933
Here is a simpler case to reproduce:
g.addV("v1")
g.V().order().by("name")
=> java.lang.IllegalArgumentException
When attempting to order vertices by property value "name" that is not defined for all vertices, we have received an unexpected exception [java.lang.IllegalArgumentException]. We have found that other Graph Databases such as HugeGraph and ArcadeDB are capable of executing similar Gremlin queries without encountering exceptions, which leads us to believe that this functionality should be supported in JanusGraph as well.
Would it be possible for you to further confirm it? It would be highly appreciated.

Best regards,
Joye

Hi Joye,

Here you go, in the gremlin console with janusgraph-0.6.3:

```
gremlin> graph = JanusGraphFactory.open('conf/janusgraph-inmemory.properties')
==>standardjanusgraph[inmemory:[127.0.0.1]]
gremlin> g = graph.traversal()
==>graphtraversalsource[standardjanusgraph[inmemory:[127.0.0.1]], standard]
gremlin> g.addV('v1')
==>v[4112]
gremlin> g.V().order().by("name")
08:00:35 WARN  org.janusgraph.graphdb.transaction.StandardJanusGraphTx - Query requires iterating over all vertices [()]. For better performance, use indexes
==>v[4112]
```

Sorry, the simple case seems that it does not work.
Here case with a little complex after-check that can cause the exception.
g.addV("v1")
g.addV("v2").property("name", "joye")
g.V().order().by("name")

Sorry for any inconvenience it caused.

Best regards,
Joye