fix(core): resolve getErrorMessage visibility and sandbox setting parsing

Moves the getErrorMessage import to the top of config.ts to avoid circularity-induced TS2304 in some environments. Also fixes a TypeError in sandbox_command.js when modern object-style sandbox settings are used in settings.json.

packages/core/src/config/config.ts

@@ -6,6 +6,7 @@
 
 import * as fs from 'node:fs';
 import * as path from 'node:path';
+import { getErrorMessage } from '../utils/errors.js';
 import { SandboxPolicyManager } from '../policy/sandboxPolicyManager.js';
 import { inspect } from 'node:util';
 import process from 'node:process';
@@ -451,7 +452,6 @@ import { McpClientManager } from '../tools/mcp-client-manager.js';
 import { A2AClientManager } from '../agents/a2a-client-manager.js';
 import { type McpContext } from '../tools/mcp-client.js';
 import type { EnvironmentSanitizationConfig } from '../services/environmentSanitization.js';
-import { getErrorMessage } from '../utils/errors.js';
 
 export type { FileFilteringOptions };
 export {

scripts/sandbox_command.js

@@ -70,7 +70,11 @@ if (!geminiSandbox) {
   geminiSandbox = process.env.GEMINI_SANDBOX;
 }
 
-geminiSandbox = (geminiSandbox || '').toLowerCase();
+if (typeof geminiSandbox === 'object' && geminiSandbox !== null) {
+  geminiSandbox = geminiSandbox.enabled ? 'true' : 'false';
+}
+
+geminiSandbox = (geminiSandbox || '').toString().toLowerCase();
 
 const commandExists = (cmd) => {
   const checkCommand = os.platform() === 'win32' ? 'where' : 'command -v';