SyncMcpToolCallback call method NPE

[Fj-ivy]

Bug description
A clear and concise description of what the bug is about.
I create mcp client to invoke @modelcontextprotocol/server-filesystem by stdio. It can invoke server-filesystem success, But when
SyncMcpToolCallback call method response field error is null, it will NPE.

Environment
Spring AI version: 1.0.0-SNAPSHOT
Java Version: 21

Steps to reproduce

• application.properties

spring.application.name=mcp-examples
 spring.ai.ollama.base-url=http://localhost:11434
 spring.ai.ollama.chat.model=qwen2.5:latest
 spring.ai.mcp.client.enabled=true
 spring.ai.mcp.client.name=mcp-client
 spring.ai.mcp.client.version=1.0.0
 spring.ai.mcp.client.type=SYNC
 spring.ai.mcp.client.request-timeout=30s
 spring.ai.mcp.client.stdio.servers-configuration=classpath:/mcp-servers-config.json

• mcp-servers-config.json

{
      "mcpServers": {
        "filesystem": {
          "command": "npx",
          "args": [
            "-y",
            "@modelcontextprotocol/server-filesystem",
            "."
          ]
        }
      }
    }

• controller

@RestController
public class FileSystemController {

    @Resource
    private OllamaChatModel ollamaChatModel;

    @Resource
    private SyncMcpToolCallbackProvider toolCallbackProvider;

    @GetMapping("/chat")
    public String call(@RequestParam String input) {
        ChatClient chatClient = ChatClient.builder(ollamaChatModel)
                .defaultTools(toolCallbackProvider.getToolCallbacks())
                .build();
        return chatClient.prompt(input).call().content();
    }
}

• visit http://localhost:8080/chat?input=create folder mcp

[Fj-ivy]

#2452