When I add use warnings; to your code like this: 
#!/usr/bin/env perl

use warnings;
use strict;

package a;

our $x = 1;

package main;

print "a::x = ", $a::x, "\n"; # Fine
print "a::z = ", $a::z, "\n"; # want to raise error here

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I get the following warning messages: 
Name "a::z" used only once: possible typo at ./647879.pl line 13.
a::x = 1
Use of uninitialized value in print at ./647879.pl line 13.
a::z =

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In reply to Re: Catch references to undefined variables in other modules? by toolic
in thread Catch references to undefined variables in other modules? by pc88mxer

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