Add spies to ensure demux handles keys correctly

src/functions/compose.ts

@@ -40,7 +40,6 @@ type AllStreams =
     | NodeJS.WritableStream;
 
 export class Compose extends Duplex {
-    public writable: boolean;
     private first: AllStreams;
     private last: AllStreams;
     private streams: AllStreams[];

src/functions/map.ts

@@ -16,7 +16,6 @@ export function map<T, R>(
                 const mapped = await mapper(chunk, encoding);
                 callback(null, mapped);
             } catch (err) {
-                console.log("caught error", err.message);
                 callback(err);
             }
         },