title: null key in from map/reduce result in couchdb
body: <p>For some reason I'm only getting a null key from map/reduce result in couchdb on mac</p>
  
  <p>Result:</p>
  
  <pre><code>{"rows":[
  {"key":null,"value":2224}
  ]}
  </code></pre>
  
  <p>Im using couchapp v8.1 and couchdb v1.0.2</p>
  
  <p>My map function is:</p>
  
  <pre><code>function(doc) {
      emit(doc.doc_type, 1);
  }
  </code></pre>
  
  <p>My reduce function is:</p>
  
  <pre><code>function(key, values, rereducer) {
    return sum(values);
  }
  </code></pre>
  
  <p>result I was expecting:</p>
  
  <pre><code>{"rows":[
  {"key":"type1","value":22}
  {"key":"type2","value":32}
  {"key":"type3","value":25}
   //snip snip
  ]}
  </code></pre>
  
  <p>Any idea where I went wrong?</p>