evaluate: Error result is truncated

When an evaluate request fails due to an error in the code being evaluated, the language server reports an unhelpful truncated message:

{
  "id": 1010,
  "format": "Cannot evaluate because of org.eclipse.debug.core.DebugException: com.sun.jdi.InvocationException occurred invoking method.."
}

Sometimes this is long enough to be useful, but for errors with longer stack traces, it's often not clear what the error actually was. Is there any way to always get the full error message?

首先跟踪 evaluate 请求的错误处理，以及生成 issue 中所示截断的 "format" 值的格式化过程。确认较长的评估失败是如何被缩短的，然后验证响应是否公开完整的错误消息，同时不丢失现有的错误上下文。