Work around incorrect 'encoding' parameter from upstream

src/transform.js

@@ -17,11 +17,12 @@ module.exports = function createTransform(file, options) {
 		let buffer = new bl.BufferList();
 
 		function chunkHandler(chunk, encoding, callback) {
-			if (encoding === "buffer") {
+			// NOTE: We check the `chunk` here, not the `encoding`, because in at least one instance a Buffer was passed in claiming to be a "utf8" string according to the `encoding` argument
+			if (Buffer.isBuffer(chunk)) {
 				buffer.append(chunk);
 				callback();
 			} else {
-				throw new Error(`Expected Buffer, got ${encoding} string instead`);
+				throw new Error(`Expected Buffer, got string instead (encoding = ${encoding})`);
 			}
 		}