打开小程序的接口，path参数不用必传

lib/data/repositories/message/open_weapp_handler.dart

@@ -19,10 +19,10 @@ class OpenWeappHandler extends MessageHandler {
     }
 
     final appid = params['appid'] as String;
-    final path = params['path'] as String;
+    final path = params['path'] as String?;
     final envVersion = params['envVersion'] as String?;
 
-    if (appid.isEmpty || path.isEmpty) {
+    if (appid.isEmpty) {
       throw Exception('参数错误');
     }
 
@@ -31,13 +31,22 @@ class OpenWeappHandler extends MessageHandler {
     }
 
     try {
-      return await _fluwx.open(
-        target: MiniProgram(
-          username: appid,
-          path: path,
-          miniProgramType: _getWXMiniProgramType(envVersion),
-        ),
-      );
+      if (path != null) {
+        return await _fluwx.open(
+          target: MiniProgram(
+            username: appid,
+            path: path,
+            miniProgramType: _getWXMiniProgramType(envVersion),
+          ),
+        );
+      } else {
+        return await _fluwx.open(
+          target: MiniProgram(
+            username: appid,
+            miniProgramType: _getWXMiniProgramType(envVersion),
+          ),
+        );
+      }
     } catch (e) {
       print(e);
       return false;