fix: don't throw if it's not a proper old-style link

We are still supporting old style links, i.e. JSON where `/` as key
signals a link. Though the JSON could could also contain such a key
without having a CID as value. Instead of throwing an error, treat it
as not being a link.

src/index.js

@@ -109,7 +109,11 @@ class IPLDResolver {
         // NOTE vmx 2018-11-29: Not all IPLD Formats return links as
         // CIDs yet. Hence try to convert old style links to CIDs
         if (Object.keys(value).length === 1 && '/' in value) {
-          value = new CID(value['/'])
+          try {
+            value = new CID(value['/'])
+          } catch (_error) {
+            value = null
+          }
         }
         cid = CID.isCID(value) ? value : null