[MODULAR] Fixes a nif related runtime with update_theme (#24392)

* Fixes a nif related runtime I saw

* Update soulcatcher.dm

* Also add some preference checking while we're at it

modular_skyrat/modules/modular_implants/code/nifsofts/soulcatcher.dm

@@ -39,6 +39,7 @@
 
 	RegisterSignal(new_soulcatcher, COMSIG_QDELETING, PROC_REF(no_soulcatcher_component))
 	linked_soulcatcher = WEAKREF(new_soulcatcher)
+	update_theme() // because we have to do this after the soulcatcher is linked
 
 /datum/nifsoft/soulcatcher/activate()
 	. = ..()
@@ -99,6 +100,9 @@
 	if(!.)
 		return FALSE // uhoh
 
+	if(isnull(linked_soulcatcher))
+		return FALSE
+
 	var/datum/component/soulcatcher/current_soulcatcher = linked_soulcatcher.resolve()
 	if(!istype(current_soulcatcher))
 		stack_trace("[src] ([REF(src)]) tried to update its theme when it was missing a linked_soulcatcher component!")

modular_skyrat/modules/modular_implants/code/soulcatcher/soulcatcher_component.dm

@@ -454,7 +454,12 @@ GLOBAL_LIST_EMPTY(soulcatchers)
 
 /mob/dead/observer/Login()
 	. = ..()
-	var/soulcatcher_action_given = client.prefs.read_preference(/datum/preference/toggle/soulcatcher_join_action)
+	var/datum/preferences/preferences = client?.prefs
+	var/soulcatcher_action_given
+
+	if(preferences)
+		soulcatcher_action_given = preferences.read_preference(/datum/preference/toggle/soulcatcher_join_action)
+
 	if(!soulcatcher_action_given)
 		return