Fix

eco-core/core-plugin/src/main/kotlin/com/willfp/ecojobs/commands/CommandJobs.kt

@@ -28,6 +28,10 @@ class CommandJobs(plugin: EcoPlugin) : PluginCommand(plugin, "jobs", "ecojobs.co
             return
         }
 
+        if (player.hasJob(job)) {
+            player.sendMessage(plugin.langYml.getMessage("dont-have-job"))
+        }
+
         job.levelGUI.open(player)
     }
 

eco-core/core-plugin/src/main/resources/lang.yml

@@ -35,6 +35,7 @@ messages:
   job-already-joined: "&cYou already have this job!"
   leave-current-job: "&cYou must leave your current job before joining a new one!"
   cant-leave-job: "&cYou can't leave the %job%&f job!"
+  dont-have-job: "&cYou don't have this job unlocked!"
 
 menu:
   title: "Jobs"