syslog-ng json parsing error

error.log

syslog-ng[1735]: json-parser(): failed to parse JSON payload; input='{"actionman": {"host": "ccosvms0110.in2p3.fr", "message": "top - 16:49:56 up 243 days, 19 min,  2 users,  load average: 0.03, 0.03, 0.05\nTasks: 161 total,   1 running, 160 sleeping,   0 stopped,   0 zombie\n%Cpu(s):  1.6 us,  1.6 sy,  0.0 ni, 96.9 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st\nKiB Mem :  8008028 total,  4668992 free,   518148 used,  2820888 buff/cache\nKiB Swap:        0 total,        0 free,        0 used.  6765456 avail Mem \n\n  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND\n17223 collectd  20   0 1066560  12548   5644 S  18.8  0.2   0:00.11 collectd\n  554 root      20   0   80436  39012  38616 S   6.2  0.5   7:13.02 systemd-jo+\n 1735 root      20   0  819240  13960   8832 S   6.2  0.2   6:43.25 syslog-ng\n17235 collectd  20   0  160948   2040   1488 R   6.2  0.0   0:00.01 top\n    1 root      20   0  191516   4520   2608 S   0.0  0.1 133:53.17 systemd\n    2 root      20   0       0      0      0 S   0.0  0.0   0:00.71 kthreadd\n    4 root       0 -20       0      0      0 S   0.0  0.0   0:00.00 kworker/0:+\n    6 root      20   0       0      0      0 S   0.0  0.0   0:02.42 ksoftirqd/0\n    7 root      rt   0       0      0      0 S   0.0  0.0   0:08.16 migration/0\n    8 root      20   0       0      0      0 S   0.0  0.0   0:00.00 rcu_bh\n    9 root      20   0       0      0      0 S   0.0  0.0  42:19.27 rcu_sched\n   10 root       0 -20       0      0      0 S   0.0  0.0   0:00.00 lru-add-dr+\n   11 root      rt   0       0      0      0 S   0.0  0.0   2:08.71 watchdog/0\n   12 root      rt   0       0      0      0 S   0.0  0.0   1:30.28 watchdog/1\n   13 root      rt   0       0      0      0 S   0.0  0.0   0:08.26 migration/1\n   14 root      20   0       0      0      0 S   0.0  0.0   0:42.18 ksoftirqd/1\n   16 root       0 -20       0      0      0 S   0.0  0.0   0:00.00 kworker/1:+\n   17 root      rt   0       0      0      0 S   0.0  0.0   1:22.06 watchdog/2\n   18 root      rt   0       0      0      0 S   0.0  0.0   0:22.56 migration/2\n   19 root      20   0       0      0      0 S   0.0  ", "meta": {"DataSource": "midterm", "CurrentValue": 0.00375, "WarningMin": NaN, "WarningMax": 10.0, "FailureMin": NaN, "FailureMax": 20.0}, "plugin": "load", "severity": 4, "time": 1637077796.5828323, "type": "load", "type_instance": "relative"}}', json_error='null expected'