Error: No applicable marginal update rule for GaussianMeanVariance node with inbound types: Message{GaussianWeightedMeanPrecision}, Message{GaussianMeanVariance}

[HoangMHNguyen]

The error happens when we compute the Free Energy for the sum-product algorithm in the "kalman_smoother_2d" demo. Possible fix: we replace @RV x[t] ~ GaussianMeanVariance(F*x_t_prev, Q) by @RV x[t] ~ GaussianMeanPrecision(F*x_t_prev, inv(Q))