Default to error code if message is non-existent

lib/plugins/aws/provider/awsProvider.js

@@ -275,7 +275,7 @@ class AwsProvider {
         req.send(cb);
       });
       return promise.catch(err => {
-        let message = err.message;
+        let message = err.message !== null ? err.message : err.code;
         if (err.message === 'Missing credentials in config') {
           const errorMessage = [
             'AWS provider credentials not found.',

lib/plugins/aws/provider/awsProvider.test.js

@@ -452,6 +452,82 @@ describe('AwsProvider', () => {
         .catch(() => done());
     });
 
+    it('should use error message if it exists', (done) => {
+      const awsErrorResponse = {
+        message: 'Something went wrong...',
+        code: 'Forbidden',
+        region: null,
+        time: '2019-01-24T00:29:01.780Z',
+        requestId: 'DAF12C1111A62C6',
+        extendedRequestId: '1OnSExiLCOsKrsdjjyds31w=',
+        statusCode: 403,
+        retryable: false,
+        retryDelay: 13.433158364430508,
+      };
+
+      class FakeS3 {
+        constructor(credentials) {
+          this.credentials = credentials;
+        }
+
+        error() {
+          return {
+            send(cb) {
+              cb(awsErrorResponse);
+            },
+          };
+        }
+      }
+      awsProvider.sdk = {
+        S3: FakeS3,
+      };
+      awsProvider.request('S3', 'error', {})
+        .then(() => done('Should not succeed'))
+        .catch((err) => {
+          expect(err.message).to.eql(awsErrorResponse.message);
+          done();
+        })
+        .catch(done);
+    });
+
+    it('should default to error code if error message is non-existent', (done) => {
+      const awsErrorResponse = {
+        message: null,
+        code: 'Forbidden',
+        region: null,
+        time: '2019-01-24T00:29:01.780Z',
+        requestId: 'DAF12C1111A62C6',
+        extendedRequestId: '1OnSExiLCOsKrsdjjyds31w=',
+        statusCode: 403,
+        retryable: false,
+        retryDelay: 13.433158364430508,
+      };
+
+      class FakeS3 {
+        constructor(credentials) {
+          this.credentials = credentials;
+        }
+
+        error() {
+          return {
+            send(cb) {
+              cb(awsErrorResponse);
+            },
+          };
+        }
+      }
+      awsProvider.sdk = {
+        S3: FakeS3,
+      };
+      awsProvider.request('S3', 'error', {})
+        .then(() => done('Should not succeed'))
+        .catch((err) => {
+          expect(err.message).to.eql(awsErrorResponse.code);
+          done();
+        })
+        .catch(done);
+    });
+
     it('should return ref to docs for missing credentials', (done) => {
       const error = {
         statusCode: 403,