plugins: fix some minor issues with the example plugins

Part-of: <https://gitlab.freedesktop.org/libinput/libinput/-/merge_requests/1354>

plugins/10-delay-motion.lua

@@ -34,7 +34,7 @@ end
 function frame(device, frame, timestamp)
     for _, v in ipairs(frame) do
         if v.usage == evdev.REL_X or v.usage == evdev.REL_Y then
-            next_time = timestamp + DELAY
+            local next_time = timestamp + DELAY
             table.insert(devices[device], {
                 time = next_time,
                 frame = frame
@@ -54,6 +54,9 @@ function device_new(device)
     if usages[evdev.REL_X] then
         devices[device] = {}
         device:connect("evdev-frame", frame)
+        device:connect("device-removed", function(dev)
+            devices[dev] = nil
+        end)
     end
 end
 

plugins/10-example.lua

@@ -31,7 +31,7 @@ function frame(device, frame, time_in_microseconds)
         -- If we get a right button event, change it to left, and
         -- vice versa. Because this happens before libinput (or the next
         -- plugin in the precedence order) sees the
-        -- frame it doesn't know that the swap happend.
+        -- frame it doesn't know that the swap happened.
         if v.usage == evdev.BTN_RIGHT then
             v.usage = evdev.BTN_LEFT
         elseif v.usage == evdev.BTN_LEFT then

plugins/10-pointer-go-slower.lua

@@ -49,5 +49,8 @@ libinput:connect("new-evdev-device", function(device)
             end
             return frame
         end)
+        device:connect("device-removed", function(dev)
+            remainders[dev] = nil
+        end)
     end
 end)