Describe the Bug/Issue
During rotation it will popup this error

To Reproduce
Just follow rotation.

Expected behavior
No UI error

Screenshots

PUT ISSUE REPORT LINK HERE:
build: v9.0.2-1.0.1
level: 39 (39)
class: WARLOCK
spec: demonology

talents: bilescourge_bombers
dark_pact
doom
soul_strike

pvptalents: call_fel_lord
call_felhunter

covenant: none

azerite: none

essences: [none], none

sets/legendaries/artifacts: none

gear: ancient_bloodmoon_cloak = 1
eternal_amulet_of_the_redeemed = 1
exquisite_sunderseer_mantle = 1
grand_staff_of_jordan = 1
karabor_sage_treads = 1
mantisweave_cord = 1
mechagonian_tabard = 1
moonstone_luck_token = 1
seal_of_sullied_mending = 1
sporebat_larval_pod = 1
steamburst_gloves = 1
steamburst_wristwraps = 1
tattered_dreadmist_leggings = 1
tattered_dreadmist_mask = 1
tattered_dreadmist_robe = 1
throbbing_swampfly_venom_sac = 1

legendaries: none

itemIDs: 107315, 108906, 112597, 112616, 112802, 113160, 113161, 114338, 122250, 122256, 122262, 122368, 122378, 122384, 122663, 174068

settings: aoe = 3
buffPadding = 0
custom1Name = Custom 1
custom2Name = Custom 2
cycle = true
cycle_min = 6
damage = true
damageDots = false
damageExpiration = 6
damagePets = false
damageRange = 0
debuffPadding = 0
enabled = true
gcdSync = true
maxRefresh = 10
maxTime = 33
nameplateRange = 8
nameplates = false
package = Demonology
petbased = false
potion = unbridled_fury
potionsReset = 20180919.1
throttleRefresh = false
throttleTime = false

toggles: cooldowns = true
custom1 = false
custom2 = false
defensives = true
essences = true
interrupts = true
mode = automatic
potions = true

PUT ERROR MESSAGE(S) HERE:
Message: ...nterface\AddOns\Hekili\Classes\WarlockDemonology.lua:247: attempt to call global 'IsKnown' (a nil value)
Time: Thu Nov 19 09:51:07 2020
Count: 41
Stack: ...nterface\AddOns\Hekili\Classes\WarlockDemonology.lua:247: attempt to call global 'IsKnown' (a nil value)
[string "=[C]"]: in function IsKnown' [string "@Interface\AddOns\Hekili\Classes\WarlockDemonology.lua"]:247: in function <...nterface\AddOns\Hekili\Classes\WarlockDemonology.lua:142> [string "@Interface\AddOns\Hekili\Classes.lua"]:699: in function handler'
[string "@interface\AddOns\Hekili\Events.lua"]:56: in function <Interface\AddOns\Hekili\Events.lua:50>

Locals:

Will fix in next build.