[main] Add error widget for 'all' errors

One exception: Wrong arguments aren't handled, because argparse doesn't
throw in this circumstance.

bumblebee-status

@@ -63,6 +63,13 @@ def main():
     output.draw('stop')
 
 if __name__ == "__main__":
+    try:
         main()
+    except Exception as e:
+        output = core.output.i3()
+        output.modules(core.module.Error(None, 'main', e))
+        output.draw('start')
+        output.update()
+        output.draw('statusline')
 
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