fix(xo-server/store): dont fail on serializing circular values

See https://github.com/vatesfr/xen-orchestra/pull/5397#discussion_r555170305

packages/xo-server/package.json

@@ -86,6 +86,7 @@
     "iterable-backoff": "^0.1.0",
     "jest-worker": "^26.3.0",
     "js-yaml": "^3.10.0",
+    "json-stringify-safe": "^5.0.1",
     "json-rpc-peer": "^0.17.0",
     "json5": "^2.0.1",
     "kindof": "^2.0.0",

packages/xo-server/src/xo-mixins/store.js

@@ -1,7 +1,11 @@
+import jsonStringifySafe from 'json-stringify-safe'
 import levelup from 'level-party'
 import sublevel from 'subleveldown'
+import { createLogger } from '@xen-orchestra/log'
 import { ensureDir } from 'fs-extra'
 
+const log = createLogger('xo:store')
+
 // ===================================================================
 
 const _levelHas = async function has(key, cb) {
@@ -27,6 +31,22 @@ const levelHas = db => {
 
 // ===================================================================
 
+const valueEncoding = {
+  buffer: false,
+  decode: JSON.parse,
+  encode: data => {
+    try {
+      return JSON.stringify(data)
+    } catch (error) {
+      log.warn(error)
+
+      // attempts to stringify by removing circular references
+      return jsonStringifySafe(data)
+    }
+  },
+  type: 'safe-json',
+}
+
 export default class {
   constructor(xo, config) {
     const dir = `${config.datadir}/leveldb`
@@ -34,10 +54,6 @@ export default class {
   }
 
   async getStore(namespace) {
-    return levelHas(
-      sublevel(await this._db, namespace, {
-        valueEncoding: 'json',
-      })
-    )
+    return levelHas(sublevel(await this._db, namespace, { valueEncoding }))
   }
 }