Yours ‘exc1’ has no data inside.
Length Class Mode
0 list list
If it was the same issue which the ‘exc1’ contains no data from the NA of mod.eco.reg$marginals.fitted.values.
I did added control.compute=list(return.marginals.predictor=TRUE) and control.predictor=list(compute=TRUE) into inla() function.
(under Model with covariates section, what i did is in the photo below)
Because by default,mod.eco.reg$marginals.fitted.values wouldn’t be produced without the command.
Hope it work for yours.