fix 从父类与overload推断当前函数返回值

Author: xuhuanzy

crates/emmylua_code_analysis/src/compilation/analyzer/unresolve/resolve_closure.rs

@@ -410,13 +410,14 @@ fn resolve_doc_function(
     if signature.resolve_return == SignatureReturnStatus::UnResolve
         || signature.resolve_return == SignatureReturnStatus::InferResolve
     {
-        signature.return_docs.clear();
-        signature.resolve_return = SignatureReturnStatus::DocResolve;
-        signature.return_docs.push(LuaDocReturnInfo {
-            name: None,
-            type_ref: doc_func.get_ret().clone(),
-            description: None,
-        });
+        if signature.return_docs.is_empty() && !doc_func.get_ret().is_nil() {
+            signature.resolve_return = SignatureReturnStatus::DocResolve;
+            signature.return_docs.push(LuaDocReturnInfo {
+                name: None,
+                type_ref: doc_func.get_ret().clone(),
+                description: None,
+            });
+        }
     }
     Some(true)
 }