Proxy server was throwing errors on socket hangups (e.g. tab closed), causing the device process to die.

lib/units/device/plugins/http.js

@@ -87,12 +87,18 @@ module.exports = syrup.serial()
                     resolver.reject(err)
                   }
 
+                  function ignore() {
+                    // No-op
+                  }
+
                   var proxy = httpProxy.createProxyServer({
                     target: url
                   , ws: false
                   , xfwd: false
                   })
 
+                  proxy.on('error', ignore)
+
                   var proxyServer = http.createServer(function(req, res) {
                       proxy.web(req, res)
                     })