File is not an image when using wp_get_image_editor

Hello,

I'm saving an image via File Upload field and it's path is stored in user metadata. So far so good.
I now need to grab that image and resize it. I'm trying to do it with wp_get_image_editor() as following: $image = wp_get_image_editor( $file ); where $file is the correct path to the image.

However, this returns the following error:

[0] => WP_Error Object
                        (
                            [errors] => Array
                                (
                                    [invalid_image] => Array
                                        (
                                            [0] => File is not an image.
                                        )

                                )

                            [error_data] => Array
                                (
                                    [invalid_image] => http://example.com/wp-content/uploads/gravity_forms/13-37ec33fbff5089a494d9ad0574a67403/2013/05/la-fitness.jpg
                                )

                        )

Any idea what might be wrong? Maybe I need to pass mime type to wp_get_image_editor()? I don't know how to do it.

I would hugely appreciate any help.

Many thanks,
Dasha