fix diagnostic MissingFields

Author: xuhuanzy

crates/emmylua_code_analysis/src/diagnostic/checker/missing_fields.rs

@@ -44,6 +44,9 @@ fn check_table_expr(
                     LuaType::Table | LuaType::Userdata => {
                         return Some(());
                     }
+                    LuaType::TableGeneric(_) => {
+                        return Some(());
+                    }
                     _ => {}
                 }
             }

crates/emmylua_code_analysis/src/diagnostic/test/missing_fields_test.rs

@@ -236,4 +236,27 @@ foo({})
         "#
         ));
     }
+
+    #[test]
+    fn test_union_table_generic() {
+        let mut ws = VirtualWorkspace::new();
+        ws.def(
+            r#"
+        ---@class RingBuffer<T>
+        ---@field a number
+        
+        ---@class LiveList<T>
+        ---@field list table<integer, T> | RingBuffer<T>
+        "#,
+        );
+        assert!(ws.check_code_for(
+            DiagnosticCode::MissingFields,
+            r#"
+            ---@type LiveList
+            local LiveList
+
+            LiveList.list = {}
+        "#
+        ));
+    }
 }