Add `...` to the end of nodes with children when debug-printing

[elenakrittik]

Cost me a day to realize that my code wasn't actually bugged, it was just that i :?-printed the node tree instead of :#?-printing it, causing me to see

ROOT_NODE@0..41

instead of the full

ROOT_NODE@0..41
  BLOCK_STMTS_NODE@0..41
    STMT_NODE@0..41
      STMT_KIND_NODE@0..41
        EXPR_NODE@0..41
          IF_EXPR_NODE@0..41
            ...

I suggest changing the debug-print to output

ROOT_NODE@0..41 ...

when ROOT_NODE has children, instead.