Fix initial fit bounds

lib/src/map/flutter_map_state.dart

@@ -78,7 +78,16 @@ class FlutterMapState extends MapGestureMixin {
     _disposeStreamGroups();
     return LayoutBuilder(
         builder: (BuildContext context, BoxConstraints constraints) {
+      var hasLateSize = mapState.hasLateSize(constraints);
+
       mapState.setOriginalSize(constraints.maxWidth, constraints.maxHeight);
+
+      // It's possible on first call to LayoutBuilder, it may not know a size
+      // which will cause methods like fitBounds to break. These methods
+      // could be called in initIfLateSize()
+      if (hasLateSize) {
+        mapState.initIfLateSize();
+      }
       var size = mapState.size;
 
       var scaleGestureTeam = GestureArenaTeam();

lib/src/map/map.dart

@@ -178,6 +178,26 @@ class MapState {
     }
   }
 
+  // Check if we've just got a new size constraints. Initially a layoutBuilder
+  // May not be able to calculate a size, and end up with 0,0
+  bool hasLateSize(constraints) {
+    if (options.bounds != null &&
+        originalSize != null &&
+        originalSize!.x == 0.0 &&
+        constraints.maxWidth != 0.0) {
+      return true;
+    }
+    return false;
+  }
+
+  // If we've just calculated a size, we may want to call some methods that
+  // rely on it, like fitBounds. Add any others here.
+  void initIfLateSize() {
+    if (options.bounds != null) {
+      fitBounds(options.bounds!, options.boundsOptions);
+    }
+  }
+
   void _handleMoveEmit(LatLng targetCenter, double targetZoom, hasGesture,
       MapEventSource source, String? id) {
     if (source == MapEventSource.flingAnimationController) {