Calling HttpService:JSONEncode with the following datatypes as a key in a table will parse them as incorrect strings.
Enums -- <null>
Enum -- <null>
EnumItem -- <token>
OverlapParams -- <null>
RotationCurveKey -- <null>
BrickColor -- <int>
CFrame -- <CoordinateFrame>
Rect -- <Rect2D>
I expect them to be in the format <typeof(KEY)> (tostring(KEY))
Repro
local HttpService = game:GetService("HttpService")
print(HttpService:JSONEncode({[Enum] = 1})) -- <null>
print(HttpService:JSONEncode({[Enum.KeyCode] = 2})) -- <null>
print(HttpService:JSONEncode({[Enum.KeyCode.One] = 3})) -- <token>
print(HttpService:JSONEncode({[OverlapParams.new()] = 4})) -- <null>
print(HttpService:JSONEncode({[RotationCurveKey.new(0, CFrame.identity, Enum.KeyInterpolationMode.Constant)] = 5})) -- <null>
print(HttpService:JSONEncode({[BrickColor.new(248, 248, 248)] = 6})) -- <int>
print(HttpService:JSONEncode({[CFrame.identity] = 7})) -- <CoordinateFrame>
print(HttpService:JSONEncode({[Rect.new()] = 8})) -- <Rect2D>
Output:
{"<null> (Enums)":1}
{"<null> (KeyCode)":2}
{"<token> (Enum.KeyCode.One)":3}
{"<null> (OverlapParams{MaxParts=false, BruteForceAllSlow=false, RespectCanCollide=false, CollisionGroup=Default, FilterDescendantsInstances={}})":4}
{"<null> ({Constant, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0})":5}
{"<int> (Institutional white)":6}
{"<CoordinateFrame> (0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1)":7}
{"<Rect2D> (0, 0, 0, 0)":8}