fix(inferium-harvester): removeFirst util

inferium-harvester.lua

@@ -62,6 +62,8 @@ local function removeFirst(t, x)
       table.insert(res, v)
     end
   end
+
+  return res
 end
 
 local function find(t, predicate)
@@ -404,6 +406,10 @@ local function replantProcedure()
     retrieveLocalPlan()
   end
 
+  if localPlan == nil then
+    error('cannot retrieve the local plan')
+  end
+
   local remotePlan = fetchRemotePlan()
 
   if remotePlan == nil then