getting a message's channel ID throws an error #11

ArgumentNullException: Value cannot be null.
Parameter name: key
System.Collections.Generic.Dictionary`2[TKey,TValue].FindEntry (TKey key) (at <b252bb13e2494f7d9e60515859634002>:0)
System.Collections.Generic.Dictionary`2[TKey,TValue].get_Item (TKey key) (at <b252bb13e2494f7d9e60515859634002>:0)
DiscordUnity.State.DiscordMessage.get_Channel () (at D:/Documents/Documents/DiscordUnity/src/DiscordUnity/State/DiscordMessage.cs:10)
...