[Bug]joern-export failed with grahson format

[tulufangrapesbrrr]

while trying to export the cfg of a code file in prahson format this error occurs:

$ joern-export cpg.bin --repr cfg --format graphson -o example_code_graph_cfg
Exception in thread "main" scala.NotImplementedError: repr=Cfg not yet supported for this format
        at io.joern.joerncli.JoernExport$.exportWithFlatgraphFormat(JoernExport.scala:161)
        at io.joern.joerncli.JoernExport$.exportCpg(JoernExport.scala:114)
        at io.joern.joerncli.JoernExport$.main$$anonfun$1$$anonfun$1(JoernExport.scala:66)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
        at scala.util.Using$.resource(Using.scala:296)
        at io.joern.joerncli.JoernExport$.main$$anonfun$1(JoernExport.scala:67)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
        at scala.Option.foreach(Option.scala:437)
        at io.joern.joerncli.JoernExport$.main(JoernExport.scala:59)
        at io.joern.joerncli.JoernExport.main(JoernExport.scala)

cdg, ddg also failed with the same error.

when --repr is set to all, the exportation was successful:

o example_code_graph
exported 91 nodes, 358 edges into /mnt/d/Code/LLM_Comment_Generation-main/example_code_graph

when --repr is set to cpg, although it seems successful but i'm not sure if the contents in the out_dir is in the right format:

dministrator@DESKTOP-VAT73EM:/mnt/d/Code/LLM_Comment_Generation-main$ joern-export cpg.bin --repr cpg --format graphson -o example_code_graph_cpg
exported 69 nodes, 265 edges into /mnt/d/Code/LLM_Comment_Generation-main/example_code_graph_cpg

I've also tried other format, dot works fine with all types of repr.

• OS：Windows+WSL(Ubuntu)

• Joern Version
  dministrator@DESKTOP-VAT73EM:/mnt/d/Code/LLM_Comment_Generation-main/joern$ joern

  ██╗ ██████╗ ███████╗██████╗ ███╗ ██╗
  ██║██╔═══██╗██╔════╝██╔══██╗████╗ ██║
  ██║██║ ██║█████╗ ██████╔╝██╔██╗ ██║
  ██ ██║██║ ██║██╔══╝ ██╔══██╗██║╚██╗██║
  ╚█████╔╝╚██████╔╝███████╗██║ ██║██║ ╚████║
  ╚════╝ ╚═════╝ ╚══════╝╚═╝ ╚═╝╚═╝ ╚═══╝
  Version: 4.0.422

• Java version:openjdk-21