Description
User reported getting this backtrace. Notice first line is a fragment message. So something is clearly wrong here. Files to reproduce are attached. This is related to unparser suspensions somehow.
```
Exception in thread "Thread-1" org.apache.daffodil.exceptions.Abort: Invariant broken. Single suspended expression making
org.apache.daffodil.exceptions.Assert$.abort(Assert.scala:120)
org.apache.daffodil.exceptions.Assert$.invariantFailed(Assert.scala:166)
org.apache.daffodil.processors.unparsers.UStateMain.evalSuspensions(UState.scala:647)
org.apache.daffodil.processors.DataProcessor.unparse(DataProcessor.scala:538)
at org.apache.daffodil.exceptions.Assert$.abort(Assert.scala:120)
at org.apache.daffodil.exceptions.Assert$.invariantFailed(Assert.scala:166)
at org.apache.daffodil.processors.unparsers.UStateMain.evalSuspensions(UState.scala:647)
at org.apache.daffodil.processors.DataProcessor.unparse(DataProcessor.scala:538)
at org.apache.daffodil.processors.DataProcessor.unparse(DataProcessor.scala:511)
at org.apache.daffodil.japi.DataProcessor.unparse(Daffodil.scala:730)
at mil.af.rl.filter.dfdl.impl.DFDLConverterImpl.translateFromXML(DFDLConverterImpl.java:130)
at mil.af.rl.filter.dfdl.TranslateFromXMLFilter.getDFDLResult(TranslateFromXMLFilter.java:47)
at mil.af.rl.filter.dfdl.DFDLFilterBase.filter(DFDLFilterBase.java:108)
```