Fix warnings from MSVC

[jimmy-park]

Following warnings are detected by MSVC Code Analysis.

• C26439 : This kind of function may not throw. Declare it noexcept.
• C26495 : Variable is uninitialized. Always initialize a member variable (type.6).
• C26498 : The function is constexpr, mark variable constexpr if compile-time evaluation is desired (con.5).

[vitaut]

Thanks for the PR. The move ctor noexcept change makes sense: merged in f4b256c. The other analysis warnings are mostly noise and can be ignored.