putAll operation index must handle invalid entries

[tabcat]

https://github.com/orbitdb/orbit-db-docstore/blob/b522ab298f95d9b0ff0e94beb4f5216c374860a5/src/DocumentIndex.js#L16-L26
In the state reducer of docstores updateIndex method, an invalid entry could be maliciously advertised to crash the method. This would likely result in the index state never being able to be update past the malicious entry.
A check should be added that makes sure item.payload.docs is iterable or an array (e.g. item.payload.docs[Symbol.iterator] or Array.isArray(item.payload.docs)).