Improve HTTP error handling

Do not throw exception on invalid/mangled URL
Provide consistent error message with the URL
on all failures.

scripts/install.js

@@ -21,11 +21,14 @@ require('../lib/extensions');
  */
 
 function download(url, dest, cb) {
-  var returnError = function(err) {
-    cb(typeof err.message === 'string' ? err.message : err);
+  var reportError = function(err) {
+    cb(['Cannot download "', url, '": ',
+      typeof err.message === 'string' ? err.message : err].join(''));
+  };
+  var successful = function(response) {
+    return response.statusCode >= 200 && response.statusCode < 300;
   };
 
-  if (url) {
   applyProxy({ rejectUnauthorized: false }, function(options) {
     options.headers = {
       'User-Agent': [
@@ -33,20 +36,24 @@ function download(url, dest, cb) {
         'node-sass-installer/', package.version
       ].join('')
     };
-      request.get(url, options).on('response', function(response) {
-        if (response.statusCode < 200 || response.statusCode >= 300) {
-          returnError(['Can not download file from:', url].join());
-          return;
+    try {
+      request(url, options, function(err, response) {
+        if (err) {
+          reportError(err);
+        } else if (!successful(response)) {
+            reportError(['HTTP error', response.statusCode, response.statusMessage].join(' '));
+        } else {
+            cb();
         }
-
+      }).on('response', function(response) {
+          if (successful(response)) {
             response.pipe(fs.createWriteStream(dest));
-
-        cb();
-      }).on('error', returnError);
+          }
       });
-  } else {
-    returnError('Download URL not defined, set SASS_BINARY_SITE in the environment to enable download.');
+    } catch (err) {
+      cb(err);
     }
+  });
 }
 
 /**