Fix regression in octocorner

docs/src/fit-interfere.md

@@ -161,5 +161,7 @@ fig
 
 Finally we can examine the joint photometry and orbit posterior as a corner plot:
 ```@example 1
+using PairPlots
+using CairoMakie: Makie
 octocorner(model, results)
 ```

src/analysis.jl

@@ -114,15 +114,15 @@ the posterior or the prior), produce a panel of 9 plots visualizing the orbits.
 The output is saved to a file based on the name of the system (`fname`).
 """
 function octoplot(model::System, ::Any)
-    error("You must load the Plots.jl package (`using Plots`) before calling this function. Then, pass your model and chain result as arguments.")
+    error("You must load the Plots.jl package (`using Plots`) before calling this function. Then, pass your model and chain result as arguments.  If you're seeing this message despite loading those packages, check that you are passing the correct argument types.")
 end
 function Octofitter.octoplot(model::Octofitter.LogDensityModel, args...; kwargs...)
     return Octofitter.octoplot(model.system, args...; kwargs...)
 end
 
 function octocorner end
 function octocorner(model::System, ::Any)
-    error("You must load the Makie package (eg `using CairoMakie`) and PairPlots package (eg `using PairPlots`) before calling this function. Then, pass your model and chain result as arguments.")
+    error("You must load the Makie package (eg `using CairoMakie`) and PairPlots package (eg `using PairPlots`) before calling this function. Then, pass your model and chain result as arguments.  If you're seeing this message despite loading those packages, check that you are passing the correct argument types.")
 end
 function Octofitter.octocorner(model::Octofitter.LogDensityModel, args...; kwargs...)
     return Octofitter.octocorner(model.system, args...; kwargs...)