image2: throws an exception if set a content with an empty figure tag

[vkmet]

Type of report

Bug

Provide detailed reproduction steps (if any)

1. Set extraPlugin as config.extraPlugins = 'image2';
2. Set a value for ckeditor as <figure class="image"></figure>

image2 plugin throws an exception if ckeditor's content contains empty "figure" tag (or if a "figure" does not contains nor "img" nor "a" tag).

<div id="editor">
    <figure class="image"></figure>
</div>

image2 expects that "figure" must always contains "img" tag or "a" tag that contains "img".
image = el.getFirst( 'img' ) || el.getFirst( 'a' ).getFirst( 'img' );
The issue can be reloved by adding additional checking:
image = el.getFirst( 'img' ) || (el.getFirst( 'a' ) && el.getFirst( 'a' ).getFirst( 'img' ));

Expected result

Exception should not be thrown.

Actual result

Uncaught TypeError: Cannot read property 'getFirst' of null exception is being thrown.

Other details

• Browser: Google Chrome 70, FireFox 62
• OS: Windows 10
• CKEditor version: ckeditor_4.10.1
• Installed CKEditor plugins: image2

[mlewand]

Actually image2 widget should not be upcasted on a figure that does not contain any img elements, as figures are not limited to images.

[Comandeer]

Merged into 4.11.2.