Implement kushuh's change preventing div by zero in removeDocumentScoreParameters

[AdventureBeard]

Implement @kushuh's proposed change in #766 , modifying removeDocumentScoreParameters to check for a divide by zero scenario before doing the calculation.

Sorry to snipe this change; just needed it badly, haha!

[vercel]

@AdventureBeard is attempting to deploy a commit to the OramaSearch Team on Vercel.

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[micheleriva]

Hi @AdventureBeard, thanks a lot for this PR! I fear that you should either do:

index.avgFieldLength[prop] = 0;

or

delete index.avgFieldLength[prop]

otherwise it'll fail type-checking as you're assigning undefined to a number property. Probably assigning to 0 is fine.

[micheleriva]

Superseeded by @#792