docs: improved documentation for camera state (#746)

Author: kikoso

README.md

@@ -157,6 +157,26 @@ Box(Modifier.fillMaxSize()) {
 }
 ```
 
+Remember that the map must load before any camera state can be set. If you are using a LaunchedEffect, you must wait until the map has been loaded:
+
+```kotlin
+@Composable
+fun MapScreen() {
+var mapLoaded by remember { mutableStateOf(false) }
+
+    GoogleMap(
+        modifier = Modifier.fillMaxSize(),
+        onMapLoaded = { mapLoaded = true }
+    )
+
+    if (mapLoaded) {
+        LaunchedEffect(Unit) {
+            // here the camera operations
+        }
+    }
+}
+```
+
 </details>
 
 <details>

maps-app/src/main/java/com/google/maps/android/compose/LocationTrackingActivity.kt

@@ -93,14 +93,16 @@ class LocationTrackingActivity : ComponentActivity() {
             // Collect location updates
             val locationState = locationFlow.collectAsState(initial = newLocation())
 
-            // Update blue dot and camera when the location changes
-            LaunchedEffect(locationState.value) {
-                Log.d(TAG, "Updating blue dot on map...")
-                locationSource.onLocationChanged(locationState.value)
-
-                Log.d(TAG, "Updating camera position...")
-                val cameraPosition = CameraPosition.fromLatLngZoom(LatLng(locationState.value.latitude, locationState.value.longitude), zoom)
-                cameraPositionState.animate(CameraUpdateFactory.newCameraPosition(cameraPosition), 1_000)
+            if (isMapLoaded) {
+                // Update blue dot and camera when the location changes
+                LaunchedEffect(locationState.value) {
+                    Log.d(TAG, "Updating blue dot on map...")
+                    locationSource.onLocationChanged(locationState.value)
+
+                    Log.d(TAG, "Updating camera position...")
+                    val cameraPosition = CameraPosition.fromLatLngZoom(LatLng(locationState.value.latitude, locationState.value.longitude), zoom)
+                    cameraPositionState.animate(CameraUpdateFactory.newCameraPosition(cameraPosition), 1_000)
+                }
             }
 
             // Detect when the map starts moving and print the reason

maps-compose/src/main/java/com/google/maps/android/compose/CameraPositionState.kt

@@ -43,7 +43,8 @@ import kotlin.coroutines.resumeWithException
 /**
  * Create and [rememberSaveable] a [CameraPositionState] using [CameraPositionState.Saver].
  * [init] will be called when the [CameraPositionState] is first created to configure its
- * initial state.
+ * initial state. Remember that the camera state can be applied when the map has been
+ * loaded.
  */
 @Composable
 public inline fun rememberCameraPositionState(