fix: markers not removed in strict mode (#15)

In strict mode, the effect-hook that creates the marker is run twice in quick succession, so we can't rely on the state to refer to the marker.

fixes #14

src/components/advanced-marker.tsx

@@ -70,24 +70,23 @@ function useAdvancedMarker(props: AdvancedMarkerProps) {
   useEffect(() => {
     if (!map || !markersLibraryReady) return;
 
-    const marker = new google.maps.marker.AdvancedMarkerElement();
-    marker.map = map;
+    const newMarker = new google.maps.marker.AdvancedMarkerElement();
+    newMarker.map = map;
 
-    setMarker(marker);
+    setMarker(newMarker);
 
     // create container for marker content if there are children
     if (numChilds > 0) {
       const el = document.createElement('div');
       if (className) el.classList.add(className);
 
-      marker.content = el;
+      newMarker.content = el;
 
       setContentContainer(el);
     }
 
     return () => {
-      if (marker) marker.map = null;
-
+      newMarker.map = null;
       setMarker(null);
       setContentContainer(null);
     };

src/components/marker.tsx

@@ -44,23 +44,18 @@ function useMarker(props: MarkerProps) {
   // create marker instance and add to the map once the map is available
   useEffect(() => {
     if (!map) {
-      if (map === undefined) {
+      if (map === undefined)
         console.error('<Marker> has to be inside a Map component.');
-      }
 
       return;
     }
 
-    const m = new google.maps.Marker(markerOptions);
-    m.setMap(map);
-    setMarker(m);
+    const newMarker = new google.maps.Marker(markerOptions);
+    newMarker.setMap(map);
+    setMarker(newMarker);
 
-    // remove from map on unmount
     return () => {
-      if (marker) {
-        marker.setMap(null);
-      }
-
+      newMarker.setMap(null);
       setMarker(null);
     };
   }, [map]);