[perl #68138] Rakudo tries to call role-parameter typename as a sub when using 'does' with a parameterized RHS && missing line# in the error

[Christian Bartolomaeus via RT]

The error has changed (same output on MoarVM and JVM):

Cannot modify an immutable TreeNode[Int]
  in method assign_pos at src/gen/m-CORE.setting:2103
  in sub postcircumfix:<[ ]> at src/gen/m-CORE.setting:3307
  in block <unit> at 68138.p6:7