return imagemin promise in clonedPipeline handler

fixes: Bluebird Warning: a promise was created in a handler but was not returned from it

Author: busticated

packages/gatsby-plugin-sharp/src/index.js

@@ -160,8 +160,7 @@ const processFile = (file, jobs, cb, reporter) => {
     ) {
       clonedPipeline
         .toBuffer()
-        .then(sharpBuffer => {
-          imagemin
+        .then(sharpBuffer => imagemin
             .buffer(sharpBuffer, {
               plugins: [
                 imageminPngquant({
@@ -175,8 +174,7 @@ const processFile = (file, jobs, cb, reporter) => {
             .then(imageminBuffer => {
               fs.writeFile(job.outputPath, imageminBuffer, onFinish)
             })
-            .catch(onFinish)
-        })
+            .catch(onFinish))
         .catch(onFinish)
       // Compress webp
     } else if (
@@ -185,16 +183,14 @@ const processFile = (file, jobs, cb, reporter) => {
     ) {
       clonedPipeline
         .toBuffer()
-        .then(sharpBuffer => {
-          imagemin
+        .then(sharpBuffer => imagemin
             .buffer(sharpBuffer, {
               plugins: [imageminWebp({ quality: args.quality })],
             })
             .then(imageminBuffer => {
               fs.writeFile(job.outputPath, imageminBuffer, onFinish)
             })
-            .catch(onFinish)
-        })
+            .catch(onFinish))
         .catch(onFinish)
       // any other format (jpeg, tiff) - don't compress it just handle output
     } else {