test: move declaration

Signed-off-by: Athan <kgryte@gmail.com>

Author: kgryte

lib/node_modules/@stdlib/_tools/eslint/rules/no-error-string-concat/test/fixtures/invalid.js

@@ -19,10 +19,9 @@
 'use strict';
 
 var invalid = [];
-var test;
 
 // Simple string concatenation in Error:
-test = {
+var test = {
 	'code': 'throw new Error( \'invalid argument. Value: `\' + value + \'`.\' );',
 	'errors': [
 		{