fix: change log level for tool execution errors

[YunKuiLu]

• Changed log level for tool execution errors from DEBUG to ERROR.

When an exception is thrown during tool execution, an ERROR-level log should be printed to help users troubleshoot the issue.
Or, should we set DEFAULT_ALWAYS_THROW to true?

[YunKuiLu]

This log comes from my habit of enabling debug level logging for org.springframework during development, which helps quickly identify issues.
But if other developers aren't used to turning on debug logs within the Spring framework, they might end up spending a lot of time troubleshooting problems.