How to define nodeCategoryProperty function for a Model in typescript?

nodeCategoryProperty function expects to have the signature –
(a: ObjectData, b?: string) => string, which, IMO, should be (a: ObjectData, b?: string) => string | undefined, as this function should not return anything if it is being used as a setter.

If the second argument is supplied, the function should modify the node data
object so that it has that new category name.

For the function I have defined –

const categoryPropertyFunction = (partData: GraphPart, category?: string): string => 
  if (category) partData.model.type = category;
  else return partData.model.type;

I am getting typescript error –

TS2366: Function lacks ending return statement and return type does not include 'undefined'.

Please help. Thanks in advance.


High-level bindings to the Valhalla framework

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