base\Model getErrors()

Attribute name. Use null to retrieve errors for all attributes.

Errors for all attributes or the specified attribute. Empty array is returned if no error. Note that when returning errors for all attributes, the result is a two-dimensional array, like the following:

[
    'username' => [
        'Username is required.',
        'Username must contain only word characters.',
    ],
    'email' => [
        'Email address is invalid.',
    ]
]