put-json: restore indent on unwinding.

The following situation is observed in the listener.

1> (put-json #H(() (a 1)))
{** print: invalid object a in JSON
 ** during evaluation at expr-1:1 of form (put-json #H(() (a 1)))
 1>
 1>

An indent established in the aborted JSON print job
has been left in the stream.

* lib.c (put_json): Save the indent value also, not
only the mode. Restore the indent mode and value
on unwinding, not just on a normal exit from out_json_rec,
similiarly to what obj_print does.

1 files changed, 7 insertions, 1 deletions

diff --git a/lib.c b/lib.c
index 07cae971..5feb7901 100644
--- a/lib.c
+++ b/lib.c
@@ -14658,8 +14658,14 @@ val put_json(val obj, val stream_in, val flat)
                   set_indent_mode(stream, num_fast(indent_foff)),
                   test_set_indent_mode(stream, num_fast(indent_off),
                                        num_fast(indent_data)));
+  val isave = get_indent(stream);
+  uw_simple_catch_begin;
   out_json_rec(obj, stream, 0);
-  set_indent_mode(stream, imode);
+  uw_unwind {
+    set_indent_mode(stream, imode);
+    set_indent(stream, isave);
+  }
+  uw_catch_end;
   return t;
 }