fix: incorrect swanctl parsing.

debian-package/src/usr/lib/vpn-router/web

@@ -91,6 +91,7 @@ def swanctl(command):
     whose value may contain spaces. Every "... event {" section at the top holds one
     connection or SA; each becomes an entry with its name under "name". The closing
     "... reply {" section is left out. Values stay strings, as swanctl prints them.
+    Output with more closing than opening lines gives None.
     """
     result = run('swanctl', command, '--pretty')
     if result is None or result.returncode != 0:
@@ -102,6 +103,8 @@ def swanctl(command):
         if not line:
             continue
         if line in ('}', ']'):
+            if not stack:
+                return None
             stack.pop()
         elif not stack:
             section = {}