Added handling for parsing errors with user-submitted HTML

fix https://linear.app/tryghost/issue/SLO-87/cannot-read-properties-of-undefined-reading-createimpl-an-unexpected
refs https://github.com/jsdom/jsdom/issues/3709

- in the event we are given some HTML to parse, and that fails, we
  currently return a HTTP 500 because it's unhandled
- the instance we saw was due to `<constructor>` crashing jsdom, we've
  opened an issue for that
- in terms of handling the error gracefully, we can surround the code
  in a try-catch and return a more suitable error. I've gone for a
  ValidationError for now - you could debate whether a different one is
  more appropriate
- also added Sentry error capturing so we're not blind to these,
  ultimately we should make sure the parser can handle all
  user-submitted data

ghost/core/core/server/api/endpoints/utils/serializers/input/pages.js

@@ -1,12 +1,20 @@
 const _ = require('lodash');
 const debug = require('@tryghost/debug')('api:endpoints:utils:serializers:input:pages');
-const mobiledoc = require('../../../../../lib/mobiledoc');
+const {ValidationError} = require('@tryghost/errors');
+const tpl = require('@tryghost/tpl');
 const url = require('./utils/url');
 const slugFilterOrder = require('./utils/slug-filter-order');
 const localUtils = require('../../index');
+const mobiledoc = require('../../../../../lib/mobiledoc');
 const postsMetaSchema = require('../../../../../data/schema').tables.posts_meta;
 const clean = require('./utils/clean');
 const lexical = require('../../../../../lib/lexical');
+const sentry = require('../../../../../../shared/sentry');
+
+const messages = {
+    failedHtmlToMobiledoc: 'Failed to convert HTML to Mobiledoc',
+    failedHtmlToLexical: 'Failed to convert HTML to Lexical'
+};
 
 function removeSourceFormats(frame) {
     if (frame.options.formats?.includes('mobiledoc') || frame.options.formats?.includes('lexical')) {
@@ -136,7 +144,17 @@ module.exports = {
                 if (process.env.CI) {
                     console.time('htmlToMobiledocConverter (page)'); // eslint-disable-line no-console
                 }
-                frame.data.pages[0].mobiledoc = JSON.stringify(mobiledoc.htmlToMobiledocConverter(html));
+
+                try {
+                    frame.data.pages[0].mobiledoc = JSON.stringify(mobiledoc.htmlToMobiledocConverter(html));
+                } catch (err) {
+                    sentry.captureException(err);
+                    throw new ValidationError({
+                        message: tpl(messages.failedHtmlToMobiledoc),
+                        err
+                    });
+                }
+
                 if (process.env.CI) {
                     console.timeEnd('htmlToMobiledocConverter (page)'); // eslint-disable-line no-console
                 }
@@ -146,7 +164,17 @@ module.exports = {
                 if (process.env.CI) {
                     console.time('htmlToLexicalConverter (page)'); // eslint-disable-line no-console
                 }
-                frame.data.pages[0].lexical = JSON.stringify(lexical.htmlToLexicalConverter(html));
+
+                try {
+                    frame.data.pages[0].lexical = JSON.stringify(lexical.htmlToLexicalConverter(html));
+                } catch (err) {
+                    sentry.captureException(err);
+                    throw new ValidationError({
+                        message: tpl(messages.failedHtmlToLexical),
+                        err
+                    });
+                }
+
                 if (process.env.CI) {
                     console.timeEnd('htmlToLexicalConverter (page)'); // eslint-disable-line no-console
                 }

ghost/core/core/server/api/endpoints/utils/serializers/input/posts.js

@@ -1,5 +1,7 @@
 const _ = require('lodash');
 const debug = require('@tryghost/debug')('api:endpoints:utils:serializers:input:posts');
+const {ValidationError} = require('@tryghost/errors');
+const tpl = require('@tryghost/tpl');
 const url = require('./utils/url');
 const slugFilterOrder = require('./utils/slug-filter-order');
 const localUtils = require('../../index');
@@ -7,6 +9,12 @@ const mobiledoc = require('../../../../../lib/mobiledoc');
 const postsMetaSchema = require('../../../../../data/schema').tables.posts_meta;
 const clean = require('./utils/clean');
 const lexical = require('../../../../../lib/lexical');
+const sentry = require('../../../../../../shared/sentry');
+
+const messages = {
+    failedHtmlToMobiledoc: 'Failed to convert HTML to Mobiledoc',
+    failedHtmlToLexical: 'Failed to convert HTML to Lexical'
+};
 
 function removeSourceFormats(frame) {
     if (frame.options.formats?.includes('mobiledoc') || frame.options.formats?.includes('lexical')) {
@@ -170,7 +178,17 @@ module.exports = {
                 if (process.env.CI) {
                     console.time('htmlToMobiledocConverter (post)'); // eslint-disable-line no-console
                 }
-                frame.data.posts[0].mobiledoc = JSON.stringify(mobiledoc.htmlToMobiledocConverter(html));
+
+                try {
+                    frame.data.posts[0].mobiledoc = JSON.stringify(mobiledoc.htmlToMobiledocConverter(html));
+                } catch (err) {
+                    sentry.captureException(err);
+                    throw new ValidationError({
+                        message: tpl(messages.failedHtmlToMobiledoc),
+                        err
+                    });
+                }
+
                 if (process.env.CI) {
                     console.timeEnd('htmlToMobiledocConverter (post)'); // eslint-disable-line no-console
                 }
@@ -180,7 +198,17 @@ module.exports = {
                 if (process.env.CI) {
                     console.time('htmlToLexicalConverter (post)'); // eslint-disable-line no-console
                 }
-                frame.data.posts[0].lexical = JSON.stringify(lexical.htmlToLexicalConverter(html));
+
+                try {
+                    frame.data.posts[0].lexical = JSON.stringify(lexical.htmlToLexicalConverter(html));
+                } catch (err) {
+                    sentry.captureException(err);
+                    throw new ValidationError({
+                        message: tpl(messages.failedHtmlToLexical),
+                        err
+                    });
+                }
+
                 if (process.env.CI) {
                     console.timeEnd('htmlToLexicalConverter (post)'); // eslint-disable-line no-console
                 }

ghost/core/test/unit/api/canary/utils/serializers/input/pages.test.js

@@ -1,7 +1,14 @@
 const should = require('should');
+const sinon = require('sinon');
 const serializers = require('../../../../../../../core/server/api/endpoints/utils/serializers');
 
+const mobiledocLib = require('@tryghost/html-to-mobiledoc');
+
 describe('Unit: endpoints/utils/serializers/input/pages', function () {
+    afterEach(function () {
+        sinon.restore();
+    });
+
     describe('browse', function () {
         it('default', function () {
             const apiConfig = {};
@@ -179,6 +186,34 @@ describe('Unit: endpoints/utils/serializers/input/pages', function () {
         frame.data.pages[0].tags.should.eql([{slug: 'slug1', name: 'hey'}, {slug: 'slug2'}]);
     });
 
+    it('throws error if HTML conversion fails', function () {
+        // JSDOM require is sometimes very slow on CI causing random timeouts
+        this.timeout(4000);
+
+        const frame = {
+            options: {
+                source: 'html'
+            },
+            data: {
+                posts: [
+                    {
+                        id: 'id1',
+                        html: '<bananarama>'
+                    }
+                ]
+            }
+        };
+
+        sinon.stub(mobiledocLib, 'toMobiledoc').throws(new Error('Some error'));
+
+        try {
+            serializers.input.posts.edit({}, frame);
+            should.fail('Error expected');
+        } catch (err) {
+            err.message.should.eql('Failed to convert HTML to Mobiledoc');
+        }
+    });
+
     describe('Ensure relations format', function () {
         it('relations is array of objects', function () {
             const apiConfig = {};

ghost/core/test/unit/api/canary/utils/serializers/input/posts.test.js

@@ -1,7 +1,14 @@
 const should = require('should');
+const sinon = require('sinon');
 const serializers = require('../../../../../../../core/server/api/endpoints/utils/serializers');
 
+const mobiledocLib = require('@tryghost/html-to-mobiledoc');
+
 describe('Unit: endpoints/utils/serializers/input/posts', function () {
+    afterEach(function () {
+        sinon.restore();
+    });
+
     describe('browse', function () {
         it('default', function () {
             const apiConfig = {};
@@ -288,6 +295,34 @@ describe('Unit: endpoints/utils/serializers/input/posts', function () {
                 let postData = frame.data.posts[0];
                 postData.lexical.should.equal('{"root":{"children":[{"children":[{"detail":0,"format":0,"mode":"normal","style":"","text":"this is great feature","type":"extended-text","version":1}],"direction":null,"format":"","indent":0,"type":"paragraph","version":1},{"type":"html","version":1,"html":"<div class=\\"custom\\">My Custom HTML</div>"},{"children":[{"detail":0,"format":0,"mode":"normal","style":"","text":"custom html preserved!","type":"extended-text","version":1}],"direction":null,"format":"","indent":0,"type":"paragraph","version":1}],"direction":null,"format":"","indent":0,"type":"root","version":1}}');
             });
+
+            it('throws error when HTML conversion fails', function () {
+                // JSDOM require is sometimes very slow on CI causing random timeouts
+                this.timeout(4000);
+
+                const frame = {
+                    options: {
+                        source: 'html'
+                    },
+                    data: {
+                        posts: [
+                            {
+                                id: 'id1',
+                                html: '<bananarama>'
+                            }
+                        ]
+                    }
+                };
+
+                sinon.stub(mobiledocLib, 'toMobiledoc').throws(new Error('Some error'));
+
+                try {
+                    serializers.input.posts.edit({}, frame);
+                    should.fail('Error expected');
+                } catch (err) {
+                    err.message.should.eql('Failed to convert HTML to Mobiledoc');
+                }
+            });
         });
 
         it('tags relation is stripped of unknown properties', function () {