Fix config schema.

package.json

@@ -152,19 +152,16 @@
 			]
 		},
 		"configuration": {
-			"type": "object",
 			"title": "LLDB",
 			"properties": {
 				"lldb.library": {
 					"markdownDescription": "Which LLDB library to use.\n\nThis can be either a file path (recommended) or a directory, in which case platform-specific heuristics will be used to locate the actual library file.",
 					"type": "string",
-					"default": null,
 					"scope": "resource"
 				},
 				"lldb.libpython": {
 					"markdownDescription": "Which Python library to use.",
 					"type": "string",
-					"default": null,
 					"scope": "resource"
 				},
 				"lldb.adapterEnv": {
@@ -752,6 +749,9 @@
 								"description": "Enable reverse debugging (Requires reverse execution support in the debug server, see User's Manual for details).",
 								"type": "boolean",
 								"default": false
+							},
+							"cargo": {
+								"type": "object"
 							}
 						}
 					}