There's only one place (added in v24.02) where we have nested subobjects, and
if the outer sub-object is not there it crashes.
```
sql: FATAL SIGNAL 11 (version v24.08rc1-2-ge134f2f-modded)
0x5781d447239b send_backtrace
common/daemon.c:33
0x5781d4472432 crashdump
common/daemon.c:75
0x787bcd64531f ???
./signal/../sysdeps/unix/sysv/linux/x86_64/libc_sigaction.c:0
0x5781d447782a json_get_membern
common/json_parse_simple.c:210
0x5781d44778cc json_get_member
common/json_parse_simple.c:223
0x5781d445d0e2 process_json_obj
plugins/sql.c:537
0x5781d445d10d process_json_obj
plugins/sql.c:538
0x5781d445d598 process_json_list
plugins/sql.c:684
0x5781d445d65a process_json_result
plugins/sql.c:699
0x5781d445d7cb default_list_done
plugins/sql.c:722
0x5781d446349d handle_rpc_reply
plugins/libplugin.c:1016
0x5781d4463640 rpc_read_response_one
plugins/libplugin.c:1202
0x5781d44636f1 rpc_conn_read_response
plugins/libplugin.c:1226
0x5781d459e56c next_plan
ccan/ccan/io/io.c:60
0x5781d459ea3d do_plan
ccan/ccan/io/io.c:422
0x5781d459eafa io_ready
ccan/ccan/io/io.c:439
0x5781d45a0469 io_loop
ccan/ccan/io/poll.c:455
0x5781d4463dcb plugin_main
plugins/libplugin.c:2230
```
Changelog-Fixed: Plugins: `sql` crash on querying `listpeerchannels` during channel establishment.
Fixes: https://github.com/ElementsProject/lightning/issues/7505
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Plugin Directory
Any file in this directory which is executable and whose name only consists of alphanumeric characters, space, '.', '-' or '_' will be automatically loaded when lightningd starts (unless suppressed with commandline options).