Throw better error for incorrect config

I get this error:

TypeError: Cannot read property 'collection' of undefined
    at /srv/node_modules/integrify/lib/rules/replicateAttributes.js:61:18
    at Array.forEach (<anonymous>)
    at /srv/node_modules/integrify/lib/rules/replicateAttributes.js:47:22
    at cloudFunctionNewSignature (/srv/node_modules/firebase-functions/lib/cloud-functions.js:105:23)
    at /worker/worker.js:825:24
    at <anonymous>
    at process._tickDomainCallback (internal/process/next_tick.js:229:7)

I have the following Firebase Cloud Function running in Node 8 environment with Typescript code:

import * as functions from 'firebase-functions';
import * as admin from 'firebase-admin';
const { integrify } = require('integrify'); 

admin.initializeApp();
const firestore = admin.firestore();
integrify({ config: { functions, firestore } });

exports.inventory_item_replicate = integrify({
    rule: 'REPLICATE_ATTRIBUTES',
    source: {
      collection: 'inventory_item',
    },
    targets: [
      {
        collection: 'cart',
        foreignKey: 'id',
        attributeMapping: { 
            'barcode': 'barcode',
            'category': 'category', 
            'image': 'image', 
            'name': 'name', 
            'price': 'price',
            'stock': 'stock',
            'type': 'type',
        },
      },
    ],
  }); 

The replication function seems to fire correctly after an update on the original collection, as I can see from the logs, and the error is logged directly afterwards:

integrify: Detected update in [inventory_item], id [QmNKvERKZI3HFEyKz3Ft], 
new value: { ...
...
...
...
integrify: On collection [cart], applying update: { ....

[anishkny]

Hey @RamiYahyaRY thanks for trying out integrify!

Could you edit the configuration line thus:

integrify({ config: { functions, db: firestore } });

integrify expects two keys in the config object: functions and db.

LMK if it works. I can enhance it to throw better error message.

[anishkny]

@devth lets continue this discussion at #56