docs: update example

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

Author: kgryte

lib/node_modules/@stdlib/_tools/eslint/rules/no-error-string-concat/examples/index.js

@@ -22,14 +22,10 @@ var Linter = require( 'eslint' ).Linter;
 var rule = require( './../lib' );
 
 var linter = new Linter();
-var result;
-var code;
-
-code = 'throw new Error( \'invalid argument. Value: `\' + value + \'`.\' );';
-
 linter.defineRule( 'no-error-string-concat', rule );
 
-result = linter.verify( code, {
+var code = 'throw new Error( \'invalid argument. Value: `\' + value + \'`.\' );';
+var result = linter.verify( code, {
 	'rules': {
 		'no-error-string-concat': 'error'
 	}