DSLX: Confusing error message when spawning unknown proc

[RobSpringer]

proc foo {
  config {
    spawn does_not_exist(...)(...);
    ()
  }
  next(tok: Token) { ... }
}

Trying to interpret this results in the error message "ParseError: Cannot find a definition for name: 'does_not_exist'", instead of "unknown proc, etc". Plz make user-friendlier.