title: Mosaicking in Google Earth Engine
body: <p>Im trying to create a mosaic in Google Earth Engine and get an error message 'b.call is not a function' on the line in which i add the layer to the map.
  Does anyone know what is going on?</p>
  <pre><code>var path38 = ee.ImageCollection(&quot;LANDSAT/LC08/C02/T1_L2&quot;)
                    .filterDate('2013-07-20', '2013-08-01')
                    .filter(ee.Filter.or(
                    ee.Filter.and(ee.Filter.eq('WRS_PATH', 38),
                    ee.Filter.eq('WRS_ROW', 25)),
                    ee.Filter.and(ee.Filter.eq('WRS_PATH', 38),
                    ee.Filter.eq('WRS_ROW', 26)),
                    ee.Filter.and(ee.Filter.eq('WRS_PATH', 38),
                    ee.Filter.eq('WRS_ROW', 27))));
  var visParams = {
    bands: ['SR_B4', 'SR_B3', 'SR_B2'],
    min: 8000,
    max: 20000,
    gamma: 2.8,
  };
  Map.addLayer(path38, visParams, 'path38SR2011');
  
  var p38mos = path38.mosaic;
  var visParams = {
    bands: ['SR_B4', 'SR_B3', 'SR_B2'],
    min: 8000,
    max: 20000,
    gamma: 2.8,
  };
  
  Map.addLayer(p38mos, visParams, 'p38_2013');
  </code></pre>