Fix #4173: glob returns an error instead of an empty list

[pragneshbagary]

Issue:
matches, err := ts.sftp.Glob(pattern) , sftp.Glob returns nil when the pattern has no hits, causing to fail schema validation with errors like

$ echo '{"jsonrpc":"2.0","id":3,"method":"tools/call","params":{"name":"glob","arguments":{"pattern":"XXX*"}}}' >&"${MCP[1]}"

$ read -t 1 -r line <&"${MCP[0]}"; jq . <<<"$line"
{
  "jsonrpc": "2.0",
  "id": 3,
  "error": {
    "code": 0,
    "message": "validating tool output: validating root: validating /properties/matches: type: <invalid reflect.Value> has type \"null\", want \"array\""
  }
}

Fix

if matches == nil {
		matches = []string{}
}

Replacing the nil value with an empty slice

Result after fix

$ echo '{"jsonrpc":"2.0","id":3,"method":"tools/call","params":{"name":"glob","arguments":{"pattern":"XXX*"}}}' >&"${MCP[1]}"

$ read -t 1 -r line <&"${MCP[0]}"; jq . <<<"$line"
{
  "jsonrpc": "2.0",
  "id": 3,
  "result": {
    "content": [
      {
        "type": "text",
        "text": "{\"matches\":[]}"
      }
    ],
    "structuredContent": {
      "matches": []
    }
  }
}

[AkihiroSuda]

Thanks