If the domain of the function \( f(x)=\sin^{-1}\!\left(\dfrac{1}{x^{2}-2x-2}\right) \) is \( (-\infty,\alpha] \cup [\beta,\gamma] \cup (\delta,\infty) \), then \( \alpha+\beta+\gamma+\delta \) is equal to:
\(5\)
\(4\)
\(3\)
\(2\)