Fix onWarning callback (#156)

example/lib/main_app.dart

@@ -42,7 +42,7 @@ class App extends StatelessWidget {
                 child: _Item(
                   child: Lottie.asset(
                     assetName,
-                    onWarning: _logger.info,
+                    onWarning: (w) => _logger.info('$assetName - $w'),
                     frameBuilder: (context, child, composition) {
                       return AnimatedOpacity(
                         opacity: composition == null ? 0 : 1,

example/pubspec.lock

@@ -14,7 +14,7 @@ packages:
       name: async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.6.1"
+    version: "2.5.0"
   boolean_selector:
     dependency: transitive
     description:

lib/src/composition.dart

@@ -99,9 +99,11 @@ class LottieComposition {
   WarningCallback? onWarning;
 
   void addWarning(String warning) {
-    _warnings.add(warning);
+    var isNew = _warnings.add(warning);
+    if (isNew) {
       onWarning?.call(warning);
     }
+  }
 
   void incrementMatteOrMaskCount(int amount) {
     _maskAndMatteCount += amount;

lib/src/lottie_builder.dart

@@ -436,9 +436,16 @@ class _LottieBuilderState extends State<LottieBuilder> {
   void _load() {
     var provider = widget.lottie;
     _loadingFuture = widget.lottie.load().then((composition) {
-      if (mounted && widget.onLoaded != null && widget.lottie == provider) {
-        composition.onWarning = widget.onWarning;
-        widget.onLoaded!(composition);
+      if (mounted && widget.lottie == provider) {
+        var onWarning = widget.onWarning;
+        composition.onWarning = onWarning;
+        if (onWarning != null) {
+          for (var warning in composition.warnings) {
+            onWarning(warning);
+          }
+        }
+
+        widget.onLoaded?.call(composition);
       }
 
       return composition;

lib/src/parser/content_model_parser.dart

@@ -84,8 +84,6 @@ class ContentModelParser {
         break;
       case 'mm':
         model = MergePathsParser.parse(reader);
-        composition.addWarning('Animation contains merge paths. '
-            'Merge paths must be manually enabled by settings enableMergePaths.');
         break;
       case 'rp':
         model = RepeaterParser.parse(reader, composition);