Error if deletion of agent fails

Project.toml

@@ -1,7 +1,7 @@
 name = "Agents"
 uuid = "46ada45e-f475-11e8-01d0-f70cc89e6671"
 authors = ["George Datseris", "Tim DuBois", "Aayush Sabharwal", "Ali Vahdati", "Adriano Meligrana"]
-version = "6.1.5"
+version = "6.1.6"
 
 [deps]
 CSV = "336ed68f-0bac-5ca0-87d4-7b16caf5d00b"

src/spaces/continuous.jl

@@ -139,6 +139,7 @@ function remove_agent_from_space!(
 )
     prev = abmspace(model).grid.stored_ids[cell_index...]
     ai = findfirst(i -> i == a.id, prev)
+    isnothing(ai) && error(lazy"Tried to remove agent with ID $(a.id) from the space, but that agent is not on the space")
     deleteat!(prev, ai)
     return a
 end

src/spaces/graph.jl

@@ -65,11 +65,13 @@ end
 #######################################################################################
 random_position(model::ABM{<:GraphSpace}) = rand(abmrng(model), 1:nv(model))
 
-function remove_agent_from_space!(agent::AbstractAgent, model::ABM{<:GraphSpace})
-    agentpos = agent.pos
+function remove_agent_from_space!(a::AbstractAgent, model::ABM{<:GraphSpace})
+    agentpos = a.pos
     ids = ids_in_position(agentpos, model)
-    deleteat!(ids, findfirst(a -> a == agent.id, ids))
-    return model
+    ai = findfirst(id -> id == a.id, ids)
+    isnothing(ai) && error(lazy"Tried to remove agent with ID $(a.id) from the space, but that agent is not on the space")
+    deleteat!(ids, ai)
+    return a
 end
 
 function add_agent_to_space!(agent::AbstractAgent, model::ABM{<:GraphSpace})