PHP Array from JSON different if only one result

I am using the Australia Post postcode loookup API which returns a JSON response.

If I search for 3094, it returns

Array
(
    [localities] => Array
        (
            [locality] => Array
                (
                    [category] => Delivery Area
                    [id] => 5588
                    [latitude] => -37.717549
                    [location] => MONTMORENCY
                    [longitude] => 145.121028
                    [postcode] => 3094
                    [state] => VIC
                )

        )

)

But, if I search for a postcode that has more than one suburb (location) associated, such as 3084, I get

Array
(
    [localities] => Array
        (
            [locality] => Array
                (
                    [0] => Array
                        (
                            [category] => Delivery Area
                            [id] => 5574
                            [latitude] => -37.739262
                            [location] => VIEWBANK
                            [longitude] => 145.096424
                            [postcode] => 3084
                            [state] => VIC
                        )

                    [1] => Array
                        (
                            [category] => Delivery Area
                            [id] => 5572
                            [latitude] => -37.756341
                            [location] => HEIDELBERG
                            [longitude] => 145.067145
                            [postcode] => 3084
                            [state] => VIC
                        )

                    [2] => Array
                        (
                            [category] => Delivery Area
                            [id] => 5573
                            [latitude] => -37.742893
                            [location] => ROSANNA
                            [longitude] => 145.065044
                            [postcode] => 3084
                            [state] => VIC
                        )

                    [3] => Array
                        (
                            [category] => Delivery Area
                            [id] => 5570
                            [latitude] => -37.7442195
                            [location] => BANYULE
                            [longitude] => 145.08793
                            [postcode] => 3084
                            [state] => VIC
                        )

                    [4] => Array
                        (
                            [category] => Delivery Area
                            [id] => 5571
                            [latitude] => -37.762519
                            [location] => EAGLEMONT
                            [longitude] => 145.068208
                            [postcode] => 3084
                            [state] => VIC
                        )

                )

        )

)

Now, after decoding via

$ch = curl_init();
curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);
curl_setopt($ch, CURLOPT_URL, $api_search_url);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_HTTPHEADER, array(
    'Auth-Key: ' . $authKey
));

$response = curl_exec($ch);
curl_close($ch);
$json_dec = json_decode($response,true);

I can do a foreach loop like

echo '<ul id="pcode_results" style="list-style:none;text-align:left;padding:10px;">';

foreach($json_dec['localities'] as $locality){
        echo '<li class="pcode_res" style="cursor:pointer;" id="' . $locality['postcode'] . ',' . $locality['location'] . ',' . $locality['state'] . '">' . $locality['postcode'] . ', ' . $locality['location'] . ', ' . $locality['state'] . '</li>';
    }

echo '</ul>';

and it seems to work when there is one result such as 3094, but not when there are multiple results like 3084.

I originally has the json decode as an object array, and doing $locality->postcode would work, but only if there was more than 1 result.

Where am I going wrong? It needs to be able to cope with both scenarios of results (1 result or more than 1) where the array structure is different.

Thank you.