这是无效的：url: places.icon, . places是一个Array，没有.icon属性。这意味着url是undefined，给出了错误：InvalidValueError: setIcon: not a string; and not an instance of PinView; and no url property; and no path property。
使用url: place.icon,代替（forEach将数组的每个元素分配给其回调函数中的place变量）。
注解（来自评论）：如果需要默认的红色标记，不要使用place响应中的图标（从marker构造函数中删除icon: icon行，以及icon对象的定义）

places.forEach(function(place) {
  if (!place.geometry) {
    console.log("Returned place contains no geometry");
    return;
  }

  let icon = {
    url: place.icon,
    size: new google.maps.Size(71, 71),
    origin: new google.maps.Point(0, 0),
    anchor: new google.maps.Point(17, 34),
    scaledSize: new google.maps.Size(25, 25)
  };

  markers.push(new google.maps.Marker({
    map: map,
    icon: icon,
    title: place.name,
    position: place.geometry.location
  }));

  if (place.geometry.viewport) {
    bounds.union(place.geometry.viewport);
  } else {
    bounds.extend(place.geometry.location);
  }
});

proof of concept fiddle

代码片段：

function initAutocomplete() {

  let map = new google.maps.Map(document.getElementById('map'), {
    center: {
      lat: 32.714286,
      lng: -117.155577
    },
    scrollwheel: false,
    zoom: 12,
    maptypeId: 'roadmap'
  });

  let input = document.getElementById('pac-input');
  let searchBox = new google.maps.places.SearchBox(input);
  map.controls[google.maps.ControlPosition.TOP_LEFT].push(input);

  map.addListener('bounds_changed', function() {
    searchBox.setBounds(map.getBounds());
  });

  let markers = [];

  searchBox.addListener('places_changed', function() {
    let places = searchBox.getPlaces();

    if (places.length == 0) {
      return;
    }

    markers.forEach(function(marker) {
      marker.setMap(null);
    });
    markers = [];

    let bounds = new google.maps.LatLngBounds();
    places.forEach(function(place) {
      if (!place.geometry) {
        console.log("Returned place contains no geometry");
        return;
      }

      let icon = {
        url: place.icon,
        size: new google.maps.Size(71, 71),
        origin: new google.maps.Point(0, 0),
        anchor: new google.maps.Point(17, 34),
        scaledSize: new google.maps.Size(25, 25)
      };

      markers.push(new google.maps.Marker({
        map: map,
        icon: icon,
        title: place.name,
        position: place.geometry.location
      }));

      if (place.geometry.viewport) {
        bounds.union(place.geometry.viewport);
      } else {
        bounds.extend(place.geometry.location);
      }
    });

    map.fitBounds(bounds);
  });
}

/* Always set the map height explicitly to define the size of the div
 * element that contains the map. */

#map {
  height: 90%;
}

/* Optional: Makes the sample page fill the window. */

html,
body {
  height: 100%;
  margin: 0;
  padding: 0;
}

#description {
  font-family: Roboto;
  font-size: 15px;
  font-weight: 300;
}

#infowindow-content .title {
  font-weight: bold;
}

#infowindow-content {
  display: none;
}

#map #infowindow-content {
  display: inline;
}

.pac-card {
  margin: 10px 10px 0 0;
  border-radius: 2px 0 0 2px;
  box-sizing: border-box;
  -moz-box-sizing: border-box;
  outline: none;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.3);
  background-color: #fff;
  font-family: Roboto;
}

#pac-container {
  padding-bottom: 12px;
  margin-right: 12px;
}

.pac-controls {
  display: inline-block;
  padding: 5px 11px;
}

.pac-controls label {
  font-family: Roboto;
  font-size: 13px;
  font-weight: 300;
}

#pac-input {
  background-color: #fff;
  font-family: Roboto;
  font-size: 15px;
  font-weight: 300;
  margin-left: 12px;
  padding: 0 11px 0 13px;
  text-overflow: ellipsis;
  width: 400px;
}

#pac-input:focus {
  border-color: #4d90fe;
}

#title {
  color: #fff;
  background-color: #4d90fe;
  font-size: 25px;
  font-weight: 500;
  padding: 6px 12px;
}

<div id="pac-container">
  <input id="pac-input" type="text" placeholder="Enter a location" value="starbuck near New York city">
</div>
<div id="map"></div>
<div id="infowindow-content">
  <img src="" width="16" height="16" id="place-icon">
  <span id="place-name" class="title"></span><br>
  <span id="place-address"></span>
</div>
<!-- Replace the value of the key parameter with your own API key. -->
<script src="https://maps.googleapis.com/maps/api/js?key=AIzaSyCkUOdZ5y7hMm0yrcCQoCvLwzdM6M8s5qk&libraries=places&callback=initAutocomplete" async defer></script>