Handle error responses from processes. Fixes #1

src/index.js

@@ -54,9 +54,21 @@ server
 
 		try {
 			const options = utils.parse(request.query, PENTHOUSE_ALLOWED_OPTIONS);
-			const cssString = await subprocess(PROCESS_FETCHCSS, {css});
+
+			const fetch = await subprocess(PROCESS_FETCHCSS, {css});
+			if (fetch.error) {
+				response.status(400).send('Error: Could not fetch css');
+				return;
+			}
+
+			const cssString = fetch.css;
 			const critical = await subprocess(PROCESS_PENTHOUSE, {...options, url, cssString});
-			response.send(critical);
+			if (critical.error) {
+				response.status(400).send('Error: Could not process page');
+				return;
+			}
+
+			response.send(critical.css);
 		} catch(error) {
 			console.error(error); // eslint-disable-line no-console
 			response.status(500).send('Error: ' + error.message);

src/process/fetchcss.js

@@ -3,6 +3,13 @@ const fetch = require('node-fetch');
 
 process.on('message', (options) => {
 	fetch(options.css)
-		.then((res) => res.text())
-		.then((css) => process.send(css));
+		.then((response) => {
+			if (response.ok) {
+				return response.text();
+			}
+
+			throw new Error(response.statusText);
+		})
+		.then((css) => process.send({css}))
+		.catch((error) => process.send({error}));
 });

src/process/penthouse.js

@@ -3,5 +3,6 @@ const penthouse = require('penthouse');
 
 process.on('message', (options) => {
 	penthouse(options)
-		.then((critical) => process.send(critical));
+		.then((css) => process.send({css}))
+		.catch((error) => process.send({error}));
 });