Error in UseMethod and Error in grid.Call.graphics about mixsiar HOT 3 OPEN

> output_JAGS(jags.1, mix, source)
Error in UseMethod("depth") : 
  no applicable method for 'depth' applied to an object of class "NULL"
In addition: Warning messages:
1: In par(usr) : argument 1 does not name a graphical parameter
2: In par(usr) : argument 1 does not name a graphical parameter
3: In par(usr) : argument 1 does not name a graphical parameter
4: In par(usr) : argument 1 does not name a graphical parameter
5: In par(usr) : argument 1 does not name a graphical parameter
6: In par(usr) : argument 1 does not name a graphical parameter
7: In par(usr) : argument 1 does not name a graphical parameter
8: In par(usr) : argument 1 does not name a graphical parameter
9: In par(usr) : argument 1 does not name a graphical parameter
10: In par(usr) : argument 1 does not name a graphical parameter

library(MixSIAR)
mixsiar.dir <- find.package("MixSIAR")
file.path(mixsiar.dir, "example_scripts")

source(file.path(mixsiar.dir, "example_scripts", "mixsiar_script_wolves.R"))

17: depth(path)
16: upViewport(depth(vp), recording = FALSE)
15: popgrobvp.viewport(x$vp)
14: popgrobvp(x$vp)
13: postDraw.grob(x)
12: postDraw(x)
11: drawGTree(x)
10: recordGraphics(drawGTree(x), list(x = x), getNamespace("grid"))
9: grid.draw.gTree(x$children[[i]], recording = FALSE)
8: grid.draw(x$children[[i]], recording = FALSE)
7: drawGTree(x)
6: recordGraphics(drawGTree(x), list(x = x), getNamespace("grid"))
5: grid.draw.gTree(gtable)
4: grid.draw(gtable)
3: print.ggplot(ggplot2::ggplot(df, ggplot2::aes(x = x, fill = sources, 
       colour = sources)) + ggplot2::geom_density(alpha = 0.3, ggplot2::aes(y = ..scaled..)) + 
       ggplot2::xlim(0, 1) + ggplot2::theme_bw() + ggplot2::xlab("Proportion of Diet") + 
       ggplot2::ylab("Scaled Posterior Density") + ggplot2::labs(title = my.title) + 
       ggplot2::theme(legend.position = c(1, 1), legend.justification = c(1, 
           1), legend.title = ggplot2::element_blank()))
2: print(ggplot2::ggplot(df, ggplot2::aes(x = x, fill = sources, 
       colour = sources)) + ggplot2::geom_density(alpha = 0.3, ggplot2::aes(y = ..scaled..)) + 
       ggplot2::xlim(0, 1) + ggplot2::theme_bw() + ggplot2::xlab("Proportion of Diet") + 
       ggplot2::ylab("Scaled Posterior Density") + ggplot2::labs(title = my.title) + 
       ggplot2::theme(legend.position = c(1, 1), legend.justification = c(1, 
           1), legend.title = ggplot2::element_blank()))
1: output_JAGS(jags.1, mix, source)