[refmt] Odd reformatting for side-effectful function and comment

Input

{
  f(i);
  /* some comment here */
}

This is the smallest input I've seen replicate the behavior. I originally found this in a for loop.

Expected Output

The { } seem redundant, so I'd expect refmt to just remove them.

f(i);
/* some comment here */

Actual Output

f(
  i,
  /* some comment here */
);

Instead it seems to try to call f with more than a single parameter, which at first sight looks like it should be an error. From utop

utop # let f x = x;;
val f : 'a -> 'a = <fun>
utop # f(1,);;
Error: Syntax error: operator expected.

Start by reproducing the smallest case with refmt using the Reason input shown, then compare its output with the expected standalone statements. Trace the formatter path responsible for comments inside a block or for-loop and verify that the result preserves the comment without turning it into an extra function argument.