(00:10:44) | BetterChat v5.2.14: Failed to load config file (is the config file corrupt?) (Additional text found in JSON string after finishing deserializing object.)
(00:10:44) | Could not initialize plugin 'BetterChat v5.2.14' (JsonSerializationException: Cannot deserialize the current JSON array (e.g. [1,2,3]) into type 'Oxide.Plugins.BetterChat+Configuration' because the type requires a JSON object (e.g. {"name":"value"}) to deserialize correctly.
To fix this error either change the JSON to a JSON object (e.g. {"name":"value"}) or change the deserialized type to an array or a type that implements a collection interface (e.g. ICollection, IList) like List<T> that can be deserialized from a JSON array. JsonArrayAttribute can also be added to the type to force it to deserialize from a JSON array.
Path '', line 1, position 1.)
  at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.EnsureArrayContract (Newtonsoft.Json.JsonReader reader, System.Type objectType, Newtonsoft.Json.Serialization.JsonContract contract) [0x00058] in <271c58b7a8684db5a2c92be17a81f252>:0

  at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateList (Newtonsoft.Json.JsonReader reader, System.Type objectType, Newtonsoft.Json.Serialization.JsonContract contract, Newtonsoft.Json.Serialization.JsonProperty member, System.Object existingValue, System.String id) [0x00012] in <271c58b7a8684db5a2c92be17a81f252>:0

  at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateValueInternal (Newtonsoft.Json.JsonReader reader, System.Type objectType, Newtonsoft.Json.Serialization.JsonContract contract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract containerContract, Newtonsoft.Json.Serialization.JsonProperty containerMember, System.Object existingValue) [0x0007f] in <271c58b7a8684db5a2c92be17a81f252>:0

  at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize (Newtonsoft.Json.JsonReader reader, System.Type objectType, System.Boolean checkAdditionalContent) [0x000d9] in <271c58b7a8684db5a2c92be17a81f252>:0

  at Newtonsoft.Json.JsonSerializer.DeserializeInternal (Newtonsoft.Json.JsonReader reader, System.Type objectType) [0x00053] in <271c58b7a8684db5a2c92be17a81f252>:0

  at Newtonsoft.Json.JsonSerializer.Deserialize (Newtonsoft.Json.JsonReader reader, System.Type objectType) [0x00000] in <271c58b7a8684db5a2c92be17a81f252>:0

  at Newtonsoft.Json.JsonConvert.DeserializeObject (System.String value, System.Type type, Newtonsoft.Json.JsonSerializerSettings settings) [0x0002d] in <271c58b7a8684db5a2c92be17a81f252>:0

  at Newtonsoft.Json.JsonConvert.DeserializeObject[T] (System.String value, Newtonsoft.Json.JsonSerializerSettings settings) [0x00000] in <271c58b7a8684db5a2c92be17a81f252>:0

  at Oxide.Core.Configuration.DynamicConfigFile.ReadObject[T] (System.String filename) [0x00028] in <b76ec77c47d1449e92b2baab8603843d>:0

  at Oxide.Plugins.BetterChat.LoadConfig () [0x0000d] in <1246b0e5d23a47fa933c486c971799ce>:0

  at Oxide.Core.Plugins.Plugin.HandleAddedToManager (Oxide.Core.Plugins.PluginManager manager) [0x0000f] in <b76ec77c47d1449e92b2baab8603843d>:0

  at Oxide.Core.Plugins.CSPlugin.HandleAddedToManager (Oxide.Core.Plugins.PluginManager manager) [0x00000] in <b76ec77c47d1449e92b2baab8603843d>:0

  at Oxide.Plugins.CSharpPlugin.HandleAddedToManager (Oxide.Core.Plugins.PluginManager manager) [0x00000] in <cd9a02fd331347bd82d550bb1a9c8e9f>:0

  at Oxide.Plugins.CovalencePlugin.HandleAddedToManager (Oxide.Core.Plugins.PluginManager manager) [0x000b3] in <cd9a02fd331347bd82d550bb1a9c8e9f>:0

  at Oxide.Core.Plugins.PluginManager.AddPlugin (Oxide.Core.Plugins.Plugin plugin) [0x00027] in <b76ec77c47d1449e92b2baab8603843d>:0

  at Oxide.Core.OxideMod.PluginLoaded (Oxide.Core.Plugins.Plugin plugin) [0x00035] in <b76ec77c47d1449e92b2baab8603843d>:0

My config file :

[
{
"GroupName": "default",
"Priority": 0,
"Title": {
"Text": "[Player]",
"Color": "#55AAFF",
"Size": 15,
"Hidden": false,
"HiddenIfNotPrimary": false
},
"Username": {
"Color": "#55AAFF",
"Size": 15
},
"Message": {
"Color": "#FFFFFF",
"Size": 15
},
"Format": {
"Chat": "{Title} {Username}: {Message}",
"Console": "{Title} {Username}: {Message}"
}
},
{
"GroupName": "vip",
"Priority": 1,
"Title": {
"Text": "[Vip]",
"Color": "#F555FF",
"Size": 15,
"Hidden": false,
"HiddenIfNotPrimary": false
},
"Username": {
"Color": "#F555FF",
"Size": 15
},
"Message": {
"Color": "#FFFFFF",
"Size": 15
},
"Format": {
"Chat": "{Title} {Username}: {Message}",
"Console": "{Title} {Username}: {Message}"
}
},
{
"GroupName": "admin",
"Priority": 2,
"Title": {
"Text": "[Admin]",
"Color": "#FF3D00",
"Size": 15,
"Hidden": false,
"HiddenIfNotPrimary": false
},
"Username": {
"Color": "#FF3D00",
"Size": 15
},
"Message": {
"Color": "#FFFFFF",
"Size": 15
},
"Format": {
"Chat": "{Title} {Username}: {Message}",
"Console": "{Title} {Username}: {Message}"
}
}
]

This is config

{
  "Maximal Titles": 3,
  "Maximal Characters Per Message": 200,
  "Reverse Title Order": false
}​

Load what you got there in data folder!