Frog case of failure on bad syntax with no diagnostic

[rakudrama]

main() {
  final x; //
  print(1);
}

$ frogsh --out=t.js bug4.dart
compilation failed with 1 errors
$

The VM gives a pretty good message:

'bug4.dart': Error: line 2 pos 9: missing initialization of 'final' variable
  final x;
        ^

[jmesserly]

Appears to have been fixed already:

/Users/jmesserly/scratch/test.dart:2:3: error: no value specified for final variable
  final x; //
  ^^^^^^^^
compilation failed with 1 errors

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Added Fixed label.