Bugme, fix error on PushNotification shutdown when it was not started:
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* Call to xpconnect wrapped JSObject produced this error:  *
[Exception... "'[JavaScript Error: "this._db is undefined" {file: "dist/bin/components/PushService.js" line: 449}]' when calling method: [nsIObserver::observe]"  nsresult: "0x80570021 (NS_ERROR_XPC_JAVASCRIPT_ERROR_WITH_DETAILS)"  location: "native frame :: <unknown filename> :: <TOP_LEVEL> :: line 0"  data: yes]
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