The Template Toolkit uses a failsafe counter to prevent runaway WHILE 
+loops which would otherwise never terminate. If the loop exceeds 1000
+ iterations then an undef exception will be thrown, reporting the err
+or:

    WHILE loop terminated (> 1000 iterations)

The $Template::Directive::WHILE_MAX variable controls this behaviour a
+nd can be set to a higher value if necessary.
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