fix: guard validateTwilioCredentials against null/non-object input

src/lib/utils/twilio-validator.js

@@ -12,6 +12,10 @@
  * @returns {{valid: boolean, errors: string[]}}
  */
 export function validateTwilioCredentials(credentials) {
+	if (!credentials || typeof credentials !== 'object') {
+		return { valid: false, errors: ['Credentials must be a non-null object'] };
+	}
+
 	const errors = [];
 
 	// Validate Account SID

tests/twilio-validator.test.js

@@ -67,6 +67,24 @@ describe('Twilio Validator', () => {
 			assert.strictEqual(result.valid, true);
 			assert.strictEqual(result.errors.length, 0);
 		});
+
+		it('should return validation failure for null input', () => {
+			const result = validateTwilioCredentials(null);
+			assert.strictEqual(result.valid, false);
+			assert.ok(result.errors.length > 0);
+		});
+
+		it('should return validation failure for undefined input', () => {
+			const result = validateTwilioCredentials(undefined);
+			assert.strictEqual(result.valid, false);
+			assert.ok(result.errors.length > 0);
+		});
+
+		it('should return validation failure for non-object input', () => {
+			const result = validateTwilioCredentials('not-an-object');
+			assert.strictEqual(result.valid, false);
+			assert.ok(result.errors.length > 0);
+		});
 	});
 
 	describe('parseTwilioError', () => {