Unhandled Exception, Invalid Operation in Modest Convert
```sh $ modest convert pctl_test.modest -O pctl_test.jani The Modest Toolset (www.modestchecker.net), version v3.1.290-gff8cae090+ff8cae0903ec136f9c4c15123e444b0b0399ff6b. Command: modest convert pctl_test.modest -O pctl_test.jani (00:00) 0···········10···········20···········30········ Optimizing automata... Unhandled exception. System.InvalidOperationException: Operation is not valid due to the current state of the object. at Modest.Automaton.ModelTypeHelper.ToString(ModelType modelType) in /home/nwad/modest/toolset/Automaton/ModelType.cs:line 130 at Modest.Automaton.AutomataNetwork.GetObjectData(ISerializer serializer) in /home/nwad/modest/toolset/Automaton/AutomataNetwork.cs:line 90 at Modest.Serialization.JsonSerializer.WriteValue(ISerializable value) in /home/nwad/modest/toolset/Serialization/JSON/JsonSerializer.cs:line 378 at Modest.Serialization.JsonSerializer.WriteValue(Object value) in /home/nwad/modest/toolset/Serialization/JSON/JsonSerializer.cs:line 144 at Modest.Serialization.JsonSerializer.Serialize(Object obj, Boolean useLongFormat, Int32 lineBreakLevels, IDictionary`2 initialContext) in /home/nwad/modest/toolset/Serialization/JSON/JsonSerializer.cs:line 28 at Modest.Automaton.NSHAModel.ToDocument(String name, OperationState operationState, IErrorHandler errors) in /home/nwad/modest/toolset/Automaton/Modularity/NSHAModel.cs:line 46 at Modest.Executable.Converter.Run(IParameterObject parameterObj, Stopwatch time, IOutputHandler outputHandler, CancellationToken cancellationTok(00:01)/home/nwad/modest/toolset/modest/Converter.cs:li····40···········50········ at Modest.Executable.Program.Main(String[] args) in /home/nwad/modest/toolset/modest/Program.cs:line 193 zsh: IOT instruction (core dumped) /home/nwad/modest/toolset/Binaries/Release/net9.0/linux-x64/modest convert - ``` Input file: [pctl_test.modest](/uploads/a44cbb3619dd5cd2dc593a44ea08bcc2/pctl_test.modest)
issue