Add some extra error handling

Author: TheMagoo73

package.json

@@ -1,6 +1,6 @@
 {
   "name": "gatsby-source-gcp-storage",
-  "version": "1.0.1",
+  "version": "1.0.2",
   "description": "Gatsby source for reading files from GCP storage buckets",
   "main": "index.js",
   "scripts": {

readme.md

@@ -5,6 +5,7 @@ A Gatsby source plugin for sourcing data into your Gatsby application from file
 [![](https://img.shields.io/npm/dm/gatsby-source-gcp-storage.svg)](https://www.npmjs.com/package/gatsby-source-gcp-storage)
 [![CircleCI](https://circleci.com/gh/TheMagoo73/gatsby-source-gcp-storage/tree/master.svg?style=svg)](https://circleci.com/gh/TheMagoo73/gatsby-source-gcp-storage/tree/master)
 [![codecov](https://codecov.io/gh/TheMagoo73/gatsby-source-gcp-storage/branch/master/graph/badge.svg)](https://codecov.io/gh/TheMagoo73/gatsby-source-gcp-storage)
+[![david](https://david-dm.org/themagoo73/gatsby-source-gcp-storage.svg)]()
 
 The plugin creates `GCPFile` nodes from files in GCP Storage. It then uses the `gatsby-source-filesystem` to download a local copy of the files from GCP, and generate `File` nodes. The various "transformer" plugins can transform the File nodes into various other types of data e.g. `gatsby-transformer-json` transforms JSON files into JSON data nodes and `gatsby-transform-remark` transforms markdown files into `MarkdownRemark` nodes from which you can query and HTML representation of the markdown.
 

src/gatsby-node.js

@@ -42,10 +42,22 @@ exports.sourceNodes = async (api, pluginOptions) => {
         return
     }
 
-    const storage = new Storage({keyFilename: gcpTokenFile})
-    const gcpBucket = storage.bucket(gcpBucketName)
+    let files
 
-    let files = await gcpBucket.getFiles({directory: storageDirectory || `/`})
+    try{
+        const storage = new Storage({keyFilename: gcpTokenFile})
+        const gcpBucket = storage.bucket(gcpBucketName)
+
+        files = await gcpBucket.getFiles({directory: storageDirectory || `/`})
+    } catch(err) {
+        reporter.panic(`
+        
+        gatsby-source-gcp-storage: unable to access storage.
+
+        The GCP storage bucket/folder could not be accessed. Ensure that the bucker and path properties are correct, and the supplied SA account token has access
+
+        `)
+    }
 
     if(files[0].length < 1) {
         reporter.warn(`gatsby-source-gcp-storage: no files to process in ${gcpBucketName}/${storageDirectory}`)