Make q close the Executor popup

Fixes #34.

Author: jackfranklin

lua/executor/executor.lua

@@ -194,12 +194,22 @@ M._make_popup = function(title, lines)
     },
   })
 
+  M._popup:map("n", "q", function()
+    M._popup:unmount()
+    M._popup = nil
+    M._state.showing_detail = false
+  end, { noremap = true, silent = true })
+
   M._popup:mount()
   Output.write_data(M._stored_task_command, M._popup.bufnr, M._settings.output_filter, lines)
 
   -- Ensure if the user uses :q or similar to destroy it, that we tidy up.
   M._popup:on({ event.BufWinLeave }, function()
     vim.schedule(function()
+      if M._popup == nil then
+        -- If the user closed the popup, we don't need to do anything.
+        return
+      end
       M._popup:unmount()
       M._popup = nil
       M._state.showing_detail = false