message: Fix nans in math::slerp.
diff: @@ -250,7 +250,13 @@ public:
  const T a = std::acos(std::abs(d) / npq);
  const T a0 = a * (1 - t);
  const T a1 = a * t;
  - const T isina = 1 / sin(a);
  + const T sina = sin(a);
  + // Prevent blowing up when slerping between two quaternions that are very near each other.
  + static constexpr T value_eps = T(10) * std::numeric_limits<T>::epsilon();
  + if (std::abs(sina) < value_eps) {
  + return lerp(p, q, t);
  + }
  + const T isina = 1 / sina;
  const T s0 = std::sin(a0) * isina;
  const T s1 = std::sin(a1) * isina;
  // ensure we're taking the "short" side
  