Yaml indentation is a part of its structure. That's actually bad

Code
<?php

use Symfony\Component\Yaml\Yaml;

$file1 'foo.yml';
$file2 'foobroken.yml';

$yml1 file_get_contents($file1);
$yml2 file_get_contents($file2);
echo 
'<h3>Yaml content</h3>';
echo 
'<h4>with correct indentation</h4>';
echo 
'<pre>' $yml1 '</pre>';
echo 
'<h4>with missing indentation</h4>';
echo 
'<pre>' $yml2 '</pre>';

echo 
'<h3>Resulting arrays</h3>';
dump(Yaml::parse($yml1), Yaml::parse($yml2));
Result

Yaml content

with correct indentation

foo:
    bar: value1
    foo: value2

with missing indentation

foo:
bar: value1
foo: value2

Resulting arrays

array:1 [
  "foo" => array:2 [
    "bar" => "value1"
    "foo" => "value2"
  ]
]
array:2 [
  "foo" => "value2"
  "bar" => "value1"
]