Migration failed because of null

[Sophietje]

Hi! I've been following the documentation to migrate a project but I'm running into a problem in the final step. The project consists of a core project which depends on 3 subprojects. I have succesfully migrated the 3 subprojects and executed the migrate-libs/scalacOptions/syntax for the core project. Unfortunately, the migrate step fails with the following error (I've truncated the error trace):

2022.02.15 10:16:04 [INFO] migrate.Scala3Migrate.compileInScala3:133 - Compilation with scala 3 failed.
Please fix the errors above.
[error]
[error] Migration of core / Compile has failed
[error] because of null
[error] dotty.tools.dotc.printing.Formatting$StringFormatter.showArg(Formatting.scala:39)
[error] dotty.tools.dotc.printing.Formatting$StringFormatter.treatArg(Formatting.scala:49)
[error] dotty.tools.dotc.printing.Formatting$StringFormatter.$anonfun$2(Formatting.scala:62)
...
[error] java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
[error] java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
[error] java.lang.Thread.run(Thread.java:748)
[error] 
[error] (internalMigrate) 
[error] Migration of core / Compile has failed
[error] because of null
[error] dotty.tools.dotc.printing.Formatting$StringFormatter.showArg(Formatting.scala:39)
[error] dotty.tools.dotc.printing.Formatting$StringFormatter.treatArg(Formatting.scala:49)
[error] dotty.tools.dotc.printing.Formatting$StringFormatter.$anonfun$2(Formatting.scala:62)
...

Possibly related is the following issue: scala/scala3#13440

I'm not sure how to continue the migration, so if you have any ideas on how to proceed that would be greatly appreciated!