When outputting variables in a template file, this type of error message appears if the variable does not exist. Below is a screenshot of the error and the solution:
- Notice: Undefined offset: 4 prompted in include() and similar
<?php if(isset($content[‘field_power’][0][‘#markup’])) { ?><span>Power:</span><?php print $content[‘field_power’][0][‘#markup’]; ?><br /><?php } ?>