message: Fix bug: avoid attaching "extends" to interface declarations.
diff: @@ -1485,7 +1485,7 @@ function genericPrintNoParens(path, options, print) {
  " "
  );
  - if (n["extends"]) {
  + if (n["extends"] && n["extends"].length > 0) {
  parts.push(
  "extends ",
  fromString(", ").join(path.map(print, "extends"))
  