Adds missing error handler that made it difficult to debug runtimes.

code/modules/admin/verbs/debug.dm

@@ -959,3 +959,13 @@
 		log_admin("[key_name(src)] has toggled [M.key]'s [blockname] block [state]!")
 	else
 		alert("Invalid mob")
+
+/datum/admins/proc/view_runtimes()
+	set category = "Debug"
+	set name = "View Runtimes"
+	set desc = "Open the Runtime Viewer"
+
+	if(!check_rights(R_DEBUG))
+		return
+
+	error_cache.showTo(usr)