fix: onResponse handler

Author: edeustace

src/file.ts

@@ -1167,8 +1167,7 @@ class File extends ServiceObject {
 
               return;
             }
-
-            const headers = rawResponseStream.toJSON().headers;
+            const headers = rawResponseStream.headers;
             const isCompressed = headers['content-encoding'] === 'gzip';
             const shouldRunValidation = !rangeRequest && (crc32c || md5);
             const throughStreams: Writable[] = [];
@@ -1185,10 +1184,10 @@ class File extends ServiceObject {
             if (throughStreams.length === 1) {
               rawResponseStream =
                   // tslint:disable-next-line:no-any
-                  (rawResponseStream.pipe(throughStreams[0]) as any);
+                  ((rawResponseStream.body as Readable).pipe(throughStreams[0]) as any);
             } else if (throughStreams.length > 1) {
               rawResponseStream =
-                  rawResponseStream.pipe(pumpify.obj(throughStreams));
+                  (rawResponseStream.body as Readable).pipe(pumpify.obj(throughStreams));
             }
 
             rawResponseStream.on('end', onComplete).pipe(throughStream, {

test/file.ts

@@ -714,10 +714,9 @@ describe('File', () => {
           (err: Error, res: {}, body: {}, callback: Function) => {
             const rawResponseStream = through();
             Object.assign(rawResponseStream, {
-              toJSON() {
-                return {headers: {}};
-              },
+                headers: {}
             });
+
             callback(null, null, rawResponseStream);
             setImmediate(() => {
               rawResponseStream.end();
@@ -937,13 +936,9 @@ describe('File', () => {
             (err: Error, res: {}, body: {}, callback: Function) => {
               const rawResponseStream = through();
               Object.assign(rawResponseStream, {
-                toJSON() {
-                  return {
-                    headers: {
-                      'content-encoding': 'gzip',
-                    },
-                  };
-                },
+                headers: {
+                  'content-encoding': 'gzip',
+                }
               });
               callback(null, null, rawResponseStream);
               setImmediate(() => {