docs(backend-integration): update import for modulepreload polyfill

[katsu223]

Description

The issue is described here - #4786

What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Before submitting the PR, please make sure you do the following

• Read the Contributing Guidelines.
• Read the Pull Request Guidelines and follow the Commit Convention.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Ideally, include relevant tests that fail without this PR but pass with it.

[ygj6]

From #4786 (comment), this approach is problematic in TS, no?

[katsu223]

@ygj6 no, TS/ts-lint just complaining about imports/etc. The issue is also reproducible on react w/o TS.
Here is the reproduction of this: https://codesandbox.io/s/5hgsj?file=/src/main.jsx
Polyfill was imported in main.jsx in order not to simulate backend. To see the error you just need to open sandbox's little browser window in new tab and open console. If the html would be rendered via backend, there would be nothing on the screen

[ygj6]

no, TS/ts-lint just complaining about imports/etc.

@katsu223 Apologise for my misleading review, I was talking about complaints from TS/ts-lint. It does fix the problem, but it also prompts the type error in TS. Not sure if this is a good solution.

[katsu223]

@ygj6, thanks for clarifications. I am not good at typescript, but I will try to dive into the problem and find the solution