Check if con exists before querying submembers

On sway, sometimes there is no focused container returned (think it happens either before or after swaylock runs), so `con` is None.

```
>autotiling
Error: 'NoneType' object has no attribute 'floating'
```

1 files changed, 16 insertions, 15 deletions

diff --git a/autotiling.py b/autotiling.py
index cca9c79..9cd6aa5 100755
--- a/autotiling.py
+++ b/autotiling.py
@@ -24,21 +24,22 @@ i3 = Connection()
 def switch_splitting(i3, e):
     try:
         con = i3.get_tree().find_focused()
-        if con.floating:                         # We're on i3: on sway it would be None
-            is_floating = '_on' in con.floating  # May be 'auto_on' or 'user_on'
-            is_full_screen = con.fullscreen_mode == 1
-        else:                                    # We are on sway
-            is_floating = con.type == 'floating_con'
-            # On sway on 1st focus the parent container returns 1, then forever the focused container itself
-            is_full_screen = con.fullscreen_mode == 1 or con.parent.fullscreen_mode == 1
-
-        is_stacked = con.parent.layout == 'stacked'
-        is_tabbed = con.parent.layout == 'tabbed'
-
-        # Let's exclude floating containers, stacked layouts, tabbed layouts and full screen mode
-        if not is_floating and not is_stacked and not is_tabbed and not is_full_screen:
-            new_layout = 'splitv' if con.rect.height > con.rect.width else 'splith'
-            i3.command(new_layout)
+        if con:
+            if con.floating:                         # We're on i3: on sway it would be None
+                is_floating = '_on' in con.floating  # May be 'auto_on' or 'user_on'
+                is_full_screen = con.fullscreen_mode == 1
+            else:                                    # We are on sway
+                is_floating = con.type == 'floating_con'
+                # On sway on 1st focus the parent container returns 1, then forever the focused container itself
+                is_full_screen = con.fullscreen_mode == 1 or con.parent.fullscreen_mode == 1
+
+            is_stacked = con.parent.layout == 'stacked'
+            is_tabbed = con.parent.layout == 'tabbed'
+
+            # Let's exclude floating containers, stacked layouts, tabbed layouts and full screen mode
+            if not is_floating and not is_stacked and not is_tabbed and not is_full_screen:
+                new_layout = 'splitv' if con.rect.height > con.rect.width else 'splith'
+                i3.command(new_layout)
 
     except Exception as e:
         print('Error: {}'.format(e))