Fallback key can be used even if fallback JSON is invalid

[marklearst]

Problem:
hasFallback is derived from fallbackFile || parsedFallbackFile. If fallbackFile is a string but invalid JSON, parsedFallbackFile becomes undefined, but hasFallback still becomes true. That forces the fallback SWR key even though fallback data can't be parsed, and the fetcher will then try a "fallback" key and "fallback" token, causing a failure.

References:

• src/contexts/FigmaVarsProvider.tsx
• src/hooks/useVariables. ts
• src/hooks/usePublishedVariables.ts
• src/utils/swrKeys.ts

Citations:

• src/contexts/FigmaVarsProvider.tsx
• src/hooks/useVariables.ts
• src/hooks/usePublishedVariables.ts
• src/utils/swrKeys.ts

Code Snippets

src/hooks/useVariables.ts:

const hasFallback = Boolean(fallbackFile || parsedFallbackFile)
const key = getVariablesKey({
  fileKey,
  token,
  providerId,
  hasFallback,
})

src/hooks/usePublishedVariables.ts:

const hasFallback = Boolean(fallbackFile || parsedFallbackFile)
const key = getPublishedVariablesKey({
  fileKey,
  token,
  providerId,
  hasFallback,
})

src/contexts/FigmaVarsProvider.tsx:

const parsedFallbackFile = useMemo(() => {
  if (!fallbackFile) return undefined
  // If already parsed (object), validate...
  if (typeof fallbackFile === 'object') { ... }
  // If string, parse JSON
  // ...
}, [fallbackFile])

src/utils/swrKeys.ts:

export function getVariablesKey(params: VariablesKeyParams): readonly [string, string] | null {
  const { fileKey, token, providerId, hasFallback } = params
  if (hasFallback) {
    return [`fallback-${providerId ?? 'default'}`, 'fallback'] as const
  }
  if (token && fileKey) {
    // ...
  }
}