for example, when calling a method on the last REPL result, it works but a spurious error is printed, also

not sure how many people even know this feature exists, but:

scala 2.13.1> List(9)
res2: List[Int] = List(9)

scala 2.13.1> .length
res3: Int = 1

whereas on JLine 3 currently:

scala> List(9)
val res1: List[Int] = List(9)

scala> .length       ^
       error: illegal start of definition

val res2: Int = 1

funny that you get the right answer anyway.

the special handling for this is in ReplCompletion#complete

there should really be test coverage.