rate a reference error as it's illegal to assign a value to an undefined
variable under such conditions ([ES5 Annex C]es5-c]):</p>
<blockquote>
<p>Assignment to an undeclared identifier or otherwise unresolvable reference
does not create a property in the global object. When a simple assignment
occurs within strict mode code, its <em>LeftHandSide</em> must not evaluate to an
unresolvable Reference. If it does a ReferenceError exception is thrown.</p>
</blockquote>
<p>If you are referring to an identifier th