WoW Version
Retail 10.1.0.50000
Skinner version beta10.50172.1

Describe the bug
I'm having a similar/identical issue as with ticket #11, but only since last update (to my knowledge) and with a different lua error.
It triggers every time I click the optional reagent for most things that I want to do, enchant onto a vellum or adding a spark to a ring craft, etc.

The lua error:

19x Skinner/RetailSupport/PlayerFrames_Retail.lua:4142: attempt to call field 'ToggleProfessionsItemFlyout' (a nil value) [string "@Skinner/RetailSupport/PlayerFrames_Retail.lua"]:4142: in function <Skinner/RetailSupport/PlayerFrames_Retail.lua:4141> [string "=(tail call)"]: ? [string "@Blizzard_ProfessionsTemplates/Blizzard_ProfessionsRecipeFlyoutInstance.lua"]:25: in function ToggleProfessionsItemFlyout'
[string "@Blizzard_ProfessionsTemplates/Blizzard_ProfessionsRecipeSchematicForm.lua"]:1213: in function <...emplates/Blizzard_ProfessionsRecipeSchematicForm.lua:1211>

Locals:
owner = Button {
0 =
SetItemButtonTexture = defined @FrameXML/ItemButtonTemplate.lua:674
SetItem = defined @Blizzard_ProfessionsTemplates/Blizzard_ProfessionsRecipeReagentSlotBase.lua:3
IconOverlay = Texture {
}
SetAlpha = defined @FrameXML/ItemButtonTemplate.lua:631
showMatchHighlight = true
locked = false
CropFrame = Texture {
}
icon = ProfessionsFrameIconTexture {
}
GetBagID = defined @FrameXML/ItemButtonTemplate.lua:643
count = 0
UpdateItemContextMatching = defined @FrameXML/ItemButtonTemplate.lua:450
SetItemButtonCount = defined @FrameXML/ItemButtonTemplate.lua:614
SetItemInternal = defined @Blizzard_ProfessionsTemplates/Blizzard_ProfessionsRecipeReagentSlotBase.lua:91
UpdateCraftedProfessionsQualityShown = defined @FrameXML/ItemButtonTemplate.lua:461
SetCurrency = defined @Blizzard_ProfessionsTemplates/Blizzard_ProfessionsRecipeReagentSlotBase.lua:8
PostOnShow = defined @FrameXML/ItemButtonTemplate.lua:414
GetItemContextOverlayMode = defined @FrameXML/ItemButtonTemplate.lua:471
SetItemSource = defined @FrameXML/ItemButtonTemplate.lua:528
IsModifyingRequired = defined @Blizzard_ProfessionsTemplates/Blizzard_ProfessionsRecipeReagentSlotBase.lua:51
ColorOverlay = Texture {
}
UpdateCursor = defined @Blizzard_ProfessionsTemplates/Blizzard_ProfessionsRecipeReagentSlotBase.lua:65
GetCurrencyID = defined @Blizzard_ProfessionsTemplates/Blizzard_ProfessionsRecipeReagentSlotBase.lua:20
SetBagID = defined @FrameXML/ItemButtonTemplate.lua:639
UpdateItemContextOverlay = defined @FrameXML/ItemButtonTemplate.lua:488
SetCropOverlayShown = defined @Blizzard_ProfessionsTemplates/Blizzard_ProfessionsRecipeReagentSlotBase.lua:43
Count = FontString {
}
SetItemButtonAnchorPoint = defined @FrameXML/ItemButtonTemplate.lua:618
searchOverlay = ProfessionsFrameSearchOverlay {
}
NormalTexture = ProfessionsFrameNormalTexture {
}
IconOverlay2 = Texture {
}
OnUpdateItemContextMatching = defined @FrameXML/ItemButtonTemplate.lua:651
OnItemContextChanged = defined @FrameXML/ItemButtonTemplate.lua:410
isModifyingRequired = false
SetModifyingRequired = defined @Blizzard_ProfessionsTemplates/Blizzard_ProfessionsRecipeReagentSlotBase.lua:47
SetItemButtonScale = defined @FrameXML/ItemButtonTemplate.lua:623
isCraftedItem = false
noProfessionQualityOverlay = false
isProfessionItem = false
HighlightTexture = Texture {
}
itemContextMatchResult = 3
InputOverlay = Frame {
}
AddIcon = Texture {
}
UpdateOverlay = defined @Blizzard_ProfessionsTemplates/Blizzard_ProfessionsRecipeReagentSlotBase.lua:55
QualityOverlay = Texture {
}
GetItemLocation = defined @FrameXML/ItemButtonTemplate.lua:610
SetItemLocation = defined @FrameXML/ItemButtonTemplate.lua:532
GetSlotAndBagID = defined @FrameXML/ItemButtonTemplate.lua:647
ItemContextOverlay = Texture {
}
Icon = Texture {
}
SetItemButtonTextureVertexColor = defined @FrameXML/ItemButtonTemplate.lua:670
GetItemID = defined @FrameXML/ItemButtonTemplate.lua:591
GetItemButtonCount = defined @FrameXML/ItemButtonTemplate.lua:627
RegisterBagButtonUpdateItemContextMatching = defined @FrameXML/ItemButtonTemplate.lua:657
SetItemButtonQuality = defined @FrameXML/ItemButtonTemplate.lua:662
PushedTexture = Texture {
}
SetLocked = defined @Blizzard_ProfessionsTemplates/Blizzard_ProfessionsRecipeReagentSlot`

fixed by beta10.50199.1