Nullpointer crash lightningd/plugin.c line 878

[m-schmoock]

Issue and Steps to Reproduce

I get these on v24.08
Not sure the exact cause and if its relevant, as I'm still struggling with other issues.
But anytime I see a Segmentation fault for whatever reason, they should be handled
at least by displaying a useful error and/or log.

(venv) pi@will-pi:~/install/lightning.git.work.24 $ ./lightningd/lightningd --offline --lightning-dir=/home/pi/.lightning.24
lightningd: FATAL SIGNAL 11 (version v24.08-modded)
0x558d56ada3 send_backtrace
	common/daemon.c:33
0x558d56ae3f crashdump
	common/daemon.c:75
0x7f85464797 ???
	???:0
0x558d538958 plugin_conn_finish
	lightningd/plugin.c:878
0x558d62eef3 destroy_conn
	ccan/ccan/io/poll.c:246
0x558d62ef1f destroy_conn_close_fd
	ccan/ccan/io/poll.c:252
0x558d63a553 notify
	ccan/ccan/tal/tal.c:246
0x558d63a63f del_tree
	ccan/ccan/tal/tal.c:437
0x558d63ac53 tal_free
	ccan/ccan/tal/tal.c:532
0x558d62d5c3 io_close
	ccan/ccan/io/io.c:496
0x558d62f6df io_loop
	ccan/ccan/io/poll.c:459
0x558d509db3 io_loop_with_timers
	lightningd/io_loop_with_timers.c:22
0x558d53a65f plugins_init
	lightningd/plugin.c:2098
0x558d50f7cb main
	lightningd/lightningd.c:1243
0x7f85007dd7 __libc_start_main
	../csu/libc-start.c:308
0x558d4e1ee7 ???
	???:0
Segmentation fault

[rustyrussell]

Ah, this is a plugin crash during startup. I'll look at it, but I've removed it from the milestone (we should exit more gracefully, but we will still probably exit!).