isLoading always typed as false when using fallbackData

[EthicalJobsJesse]

Bug report

Description / Observed Behavior

isLoading is typed as false when using fallbackData

Expected Behavior

According to https://swr.vercel.app/docs/advanced/understanding#fallback, when fallbackData is set it will still run the initial fetch, and sLoading will be true while that's happening. When checking the values for isLoading this is what happens. However the type doesn't match, meaning we currently need to disable linting checks or cast isLoading to a boolean.

Repro Steps / Code Example

const { data, isLoading } = useSWR('key', () => Promise.resolve([]), { fallbackData: [] });

Checking the type isLoading it will be reported as false rather that boolean. If you remove fallbackData the type will correctly be reported as boolean

Additional Context

SWR version: v2.2.4