[Bug] isAtStart throws an error when deleting content.

[vincentdesmares]

Sometimes when you delete content, a bug appears:

TypeError
Cannot read property 'length' of undefined

Error source:

{snip} tion(t){var e=d.default.isLineBreakTag(t),n=1===t.children.length&&d.default.isLineBreakTag(t.children[0]),o=e||n;return d.default.isEmpty(t {snip}

Which is the minified version of:

  const leftSiblings = this.getHigherLevelSiblings(focusNode as HTMLElement, 'left');
      const nothingAtLeft = leftSiblings.every((node) => {
        /**
         * Workaround case when block starts with several <br>'s (created by SHIFT+ENTER)
         *
         * @see https://github.com/codex-team/editor.js/issues/726
         * We need to allow to delete such linebreaks, so in this case caret IS NOT AT START
         */
        const regularLineBreak = $.isLineBreakTag(node);
        /**
         * Workaround SHIFT+ENTER in Safari, that creates <div><br></div> instead of <br>
         */
        const lineBreakInSafari = node.children.length === 1 && $.isLineBreakTag(node.children[0] as HTMLElement);
        const isLineBreak = regularLineBreak || lineBreakInSafari;

        return $.isEmpty(node) && !isLineBreak;
      });

Last action of the user:

div.ce-block__content > div.ce-paragraph.cdx-block

Expected behavior:

The deletion should work.

Device, Browser, OS: Chrome 83.0.4103, Mac OS X 10.14.6

Editor.js version:

    "@editorjs/checklist": "^1.1.0",
    "@editorjs/editorjs": "^2.17.0",
    "@editorjs/embed": "^2.3.1",
    "@editorjs/header": "^2.4.1",
    "@editorjs/image": "^2.3.4",
    "@editorjs/link": "^2.1.3",
    "@editorjs/list": "^1.4.0",
    "@editorjs/marker": "^1.2.2",
    "@editorjs/quote": "^2.3.0",
    "@editorjs/warning": "^1.1.1",

[nikolassoares]

try others versions of Editor.js, and plugins, it's works for me

[StarAzure]

Getting the same error at

n = 1 === t.children.length && f.default.isLineBreakTag(t.children[0]),

TypeError: Cannot read property 'length' of undefined

To reproduce, enter key on a non text node for a new line and immediately hit backspace to delete the new line.

[chrisparnin]

Gif recording of the same error. Seems having issue with backspace + contenteditable items (and deleting line break content).

Code from stack trace, crashing inside the function passed to the .every() call:

{key:"isAtStart",get:function()
{
var t=c.default.get(),
e=f.default.getDeepestNode(this.Editor.BlockManager.currentBlock.currentInput),
n=t.focusNode;

if(f.default.isNativeInput(e))
	return 0===e.selectionEnd;

if(!t.anchorNode)return!1;var o=n.textContent.search(/\S/);-1===o&&(o=0);var r=t.focusOffset;

return n.nodeType!==Node.TEXT_NODE&&n.childNodes.length&&(n.childNodes[r]?(n=n.childNodes[r],r=0):r=(n=n.childNodes[r-1]).textContent.length),

!(!f.default.isLineBreakTag(e)&&!f.default.isEmpty(e)||!this.getHigherLevelSiblings(n,"left")
.every((function(t)
{var e=f.default.isLineBreakTag(t),
n=1===t.children.length&&f.default.isLineBreakTag(t.children[0]),o=e||n;
return f.default.isEmpty(t)&&!o}))||r!==o)||(null===e||n===e&&r<=o)}}

[chrisparnin]

Fix might be to simply guard the reference to focusNode.childNodes.length:

editor.js/src/components/modules/caret.ts

Line 89 in 9cdda11

if (focusNode.nodeType !== Node.TEXT_NODE && focusNode.childNodes.length) {