fix(decoder): rethrow a more helpful error if Buffer is undefined (jp…

…eg-js#93)

lib/decoder.js

@@ -1123,13 +1123,19 @@ function decode(jpegData, userOpts = {}) {
     if(decoder.comments.length > 0) {
       image["comments"] = decoder.comments;
     }
-  } catch (err){
-    if (err instanceof RangeError){
+  } catch (err) {
+    if (err instanceof RangeError) {
       throw new Error("Could not allocate enough memory for the image. " +
                       "Required: " + bytesNeeded);
-    } else {
-      throw err;
+    } 
+
+    if (err instanceof ReferenceError) {
+      if (err.message === "Buffer is not defined") {
+        throw new Error("Buffer is not globally defined in this environment. " +
+                        "Consider setting useTArray to true");
+      }
     }
+    throw err;
   }
 
   decoder.copyToImageData(image, opts.formatAsRGBA);