When saving fails, editor.save() resolves the promise (instead of rejecting it)

Steps to reproduce:
1. raise an exception in a Editor.js block in its save() method
2. Editor.js properly detects and logs the error in the console. For example: `Saving failed due to the Error TypeError: Cannot read properties of null (reading 'src')`
3. Editor.js then invokes and resolves the `editor.save().then()` promise with null content

**Expected behavior:**

Editor.js should reject the promise so that the `catch` code is executed for that promise.

**Actual behavior:**

Editor.js fulfill the promise and the `then` code block is executed for that promise.

**Device, Browser, OS**: All

**Editor.js version**: 2.29