Failed to call hook 'OnFlameExplosion' on plugin 'DeathNotes v6.3.7' (NullReferenceException: Object reference not set to an instance of an object)
  at Oxide.Plugins.DeathNotes.OnFlameExplosion (FlameExplosive explosive, BaseEntity baseEntity) [0x00000] in <ead76ccc31a04e7783021be48781b347>:0 
  at Oxide.Plugins.DeathNotes.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x0023f] in <ead76ccc31a04e7783021be48781b347>:0 
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <09575a60985045248bcb43b20faeeb99>:0 
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <bae5f1223fce49c493b01571c99dce02>:0 
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <bae5f1223fce49c493b01571c99dce02>:0

On latest rust update

confirmed getting the same spamming into console

Failed to call hook 'OnFlameExplosion' on plugin 'DeathNotes v6.3.7' (NullReferenceException: Object reference not set to an instance of an object)

at Oxide.Plugins.DeathNotes.OnFlameExplosion (FlameExplosive explosive, BaseEntity baseEntity) [0x00000] in <f0b1ba7e5576460eb0a09ac872e63298>:0

at Oxide.Plugins.DeathNotes.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x0023f] in <f0b1ba7e5576460eb0a09ac872e63298>:0

at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <09575a60985045248bcb43b20faeeb99>:0

at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <bae5f1223fce49c493b01571c99dce02>:0

Fix until updated, replace:

var flame = baseEntity.gameObject.AddComponent<Flame>();​

on line 243 with:

var flame = baseEntity?.gameObject?.AddComponent<Flame>();
if (flame == null)
    return;​