Playground: Syntax highlighting breakage for polyvar usage in external

[ryyppy]

Following example breaks the highlighter at #"best fit"

@obj
external dateTimeFormatOptions: (
  ~localeMatcher: [#"best fit" | #lookup]=?,
  ~formatMatcher: [@as("best fit") #bestFit | #basic]=?,
  ~timeZone: string=?,
  ~hour12: bool=?,
  ~weekday: [#narrow | #short | #long]=?,
  ~era: [#narrow | #short | #long]=?,
  ~year: [#numeric | @as("2-digit") #twoDigit]=?,
  ~month: [
    | #numeric
    | @as("2-digit") #twoDigit
    | #narrow
    | #short
    | #long
  ]=?,
  ~day: [#numeric | @as("2-digit") #twoDigit]=?,
  ~hour: [#numeric | @as("2-digit") #twoDigit]=?,
  ~minute: [#numeric | @as("2-digit") #twoDigit]=?,
  ~second: [#numeric | @as("2-digit") #twoDigit]=?,
  ~timeZoneName: [#short | #long]=?,
  ~format: string=?,
  unit,
) => dateTimeFormatOptions = ""

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