From e37047708cece5a459d79c6fa152eadc7a1890aa Mon Sep 17 00:00:00 2001
From: Erik Faulhaber <44124897+efaulhaber@users.noreply.github.com>
Date: Wed, 15 Nov 2023 15:21:45 +0100
Subject: [PATCH] Add comment and more specific error in  `convergence_test`

---
 src/auxiliary/special_elixirs.jl | 25 ++++++++++++++++++-------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/src/auxiliary/special_elixirs.jl b/src/auxiliary/special_elixirs.jl
index 75e52aaf029..c95c9ff2dfd 100644
--- a/src/auxiliary/special_elixirs.jl
+++ b/src/auxiliary/special_elixirs.jl
@@ -290,14 +290,25 @@ function extract_initial_resolution(elixir, kwargs)
             return initial_refinement_level
         end
     catch e
+        # If `initial_refinement_level` is not found, we will get an `ArgumentError`
         if isa(e, ArgumentError)
-            # get cells_per_dimension from the elixir
-            cells_per_dimension = eval(find_assignment(expr, :cells_per_dimension))
-
-            if haskey(kwargs, :cells_per_dimension)
-                return kwargs[:cells_per_dimension]
-            else
-                return cells_per_dimension
+            try
+                # get cells_per_dimension from the elixir
+                cells_per_dimension = eval(find_assignment(expr, :cells_per_dimension))
+
+                if haskey(kwargs, :cells_per_dimension)
+                    return kwargs[:cells_per_dimension]
+                else
+                    return cells_per_dimension
+                end
+            catch e2
+                # If `cells_per_dimension` is not found either
+                if isa(e2, ArgumentError)
+                    throw(ArgumentError("`convergence_test` requires the elixir to define " *
+                                        "`initial_refinement_level` or `cells_per_dimension`"))
+                else
+                    throw(e2)
+                end
             end
         else
             throw(e)