fix: better graphql handler (#40)

Co-authored-by: TakahashiNg <83152264+TakahashiNguyen@users.noreply.github.com>
Reviewed-on: #40

gateway-service/src/main/java/com/drinkool/controller/EateryController.java

@@ -2,11 +2,14 @@ package com.drinkool.controller;
 
 import com.drinkool.dtos.GraphqlDto;
 import io.smallrye.graphql.client.GraphQLClient;
+import io.smallrye.graphql.client.GraphQLError;
 import io.smallrye.graphql.client.dynamic.api.DynamicGraphQLClient;
 import jakarta.ws.rs.POST;
 import jakarta.ws.rs.Path;
 import jakarta.ws.rs.core.Response;
+import java.util.List;
 import java.util.concurrent.ExecutionException;
+import java.util.stream.Collectors;
 
 @Path("/api/eatery")
 public class EateryController {
@@ -24,9 +27,13 @@ public class EateryController {
 		);
 
 		if (response.hasError()) {
-			return jakarta.ws.rs.core.Response.status(500)
-				.entity(response.getErrors())
-				.build();
+			List<String> errorMessages = response
+				.getErrors()
+				.stream()
+				.map(GraphQLError::getMessage)
+				.collect(Collectors.toList());
+
+			return Response.status(400).entity(errorMessages).build();
 		}
 
 		return jakarta.ws.rs.core.Response.ok(