[SUGGESTION] Cleaned up search index & json module

[Didas-git]

Description

Since i commented about this I decided to take a look and cleanup the file a bit. This should be taken with a grain of salt bcz its purelly based on my opinion.

Also implemented all the changes in #1901 and the suggestion i commented about, keyof any to PropertyKey

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Checklist

• [x] Does npm test pass with this change (including linting)?
• [x] Is the new or changed code fully tested?
• [x] Is a documentation update included (if this change modifies existing APIs, or introduces new ones)?

[Didas-git]

I also thought about changing some of the if statements to &&