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Typescript: Not all constituents of type ‘boolean | (() => void)’ are callable

The full error:

This expression is not callable.  Not all constituents of type 'boolean | (() => void)' are callable.    Type 'false' has no call signatures.  TS2349

This is the code that was triggering the error:

export const useLoading = (defaultValue: boolean = false) => {
    const [loading, setLoading ] = useState(defaultValue)

    const startLoading = () => setLoading(true)
    const stopLoading = () => setLoading(false)

    return [
        loading,
        startLoading,
        stopLoading
    ]
}

CAUSE: the return of the array. Having arrays without a specific type gave me this error as wel: Line 0: Parsing error: : Cannot read property ‘map’ of undefined. The solution was to typehint the array.

SOLUTION: don’t return the array just like that, add ‘as const` at the end of that return statement.

export const useLoading = (defaultValue: boolean = false) => {
    const [loading, setLoading ] = useState(defaultValue)

    const startLoading = () => setLoading(true)
    const stopLoading = () => setLoading(false)

    return [
        loading,
        startLoading,
        stopLoading
    ] as const
}

This is the post that showed me where to find it: https://github.com/microsoft/TypeScript/issues/35423

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