add a undefined JSON replacer for diff

packages/health-check/src/checks/verbose.js

@@ -2,7 +2,7 @@ const superagent = require("superagent");
 const hash = require("object-hash");
 const { detailedDiff } = require("deep-object-diff");
 const { isEqual } = require("lodash");
-const { calculateElapsedTime, getResponseContent } = require("../utils");
+const { calculateElapsedTime, ensureValidJSON, getResponseContent } = require("../utils");
 
 // audioExampleCheck returns the result of trying to download the skylink
 // for the Example audio file on siasky.net
@@ -918,7 +918,7 @@ function skylinkVerification(done, { name, skylink, bodyHash, metadata }) {
         if (!isEqual(currentMetadata, metadata)) {
           entry.up = false;
 
-          info.metadata = detailedDiff(metadata, currentMetadata);
+          info.metadata = ensureValidJSON(detailedDiff(metadata, currentMetadata));
         }
 
         if (Object.keys(info).length) entry.info = info; // add info only if it exists

packages/health-check/src/utils.js

@@ -29,8 +29,19 @@ function getResponseContent(response) {
   }
 }
 
+/**
+ * Ensures that the object serializes to JSON properly
+ */
+function ensureValidJSON(object) {
+  const replacer = (key, value) => (value === undefined ? "--undefined--" : value);
+  const stringified = JSON.stringify(object, replacer);
+
+  return JSON.parse(stringified);
+}
+
 module.exports = {
   calculateElapsedTime,
   getYesterdayISOString,
   getResponseContent,
+  ensureValidJSON,
 };