fix bug

example/ios/Podfile.lock

@@ -19,4 +19,4 @@ SPEC CHECKSUMS:
 
 PODFILE CHECKSUM: 348e15598a1c6ea25d3ed63919d5ffb9bd1c2ba6
 
-COCOAPODS: 1.7.3
+COCOAPODS: 1.7.5

lib/src/models/wechat_share_models.dart

@@ -193,7 +193,6 @@ class WeChatShareImageModel extends WeChatShareModel {
       : this.image = "file://${imageFile.path}",
         this.transaction = transaction ?? "text",
         this.thumbnail = thumbnail ?? "",
-        assert(image != null),
         super(
           mediaTagName: mediaTagName,
           messageAction: messageAction,