Source object is ignored if it has a type other than a regular "object" about deepmerge-ts

[RebeccaStevens]

This is actually intended behavior, and is considered a feature of this library.
This is because in general, we have no idea how to merge non-record objects. If you want to handle such objects, you need to tell the library how it should merge them by defining a custom merger with deepmergeCustom.

If you want to simply treat all objects as records, you can use the following:

import { deepmergeCustom, type DeepMergeLeaf, type DeepMergeRecordsDefaultHKT } from "deepmerge-ts";

declare module "deepmerge-ts" {
  interface DeepMergeMergeFunctionURItoKind<
    Ts extends ReadonlyArray<unknown>,
    MF extends DeepMergeMergeFunctionsURIs,
    M
  > {
    readonly DeepMergeLeafTreatAllObjectsAsReocrdsURI: Ts[number] extends object
      ? DeepMergeRecordsDefaultHKT<{ [I in keyof Ts]: { [J in keyof Ts[I]]: Ts[I][J]; }; }, MF, M >
      : DeepMergeLeaf<Ts>;
  }
}

export const deepmergeObjectsAsRecords = deepmergeCustom<{
  DeepMergeOthersURI: "DeepMergeLeafTreatAllObjectsAsReocrdsURI";
}>({
  mergeOthers: (values, utils, meta) => {
    let allObjects = true;

    // Convert all objects to records.
    const asRecords = values.map((v) => {
      if (typeof v === "object" && v !== null) {
        return { ...v };
      }
      allObjects = false;
      return false;
    });

    // If only merging objects, merge them as records.
    if (allObjects) {
      return utils.mergeFunctions.mergeRecords(asRecords, utils, meta);
    }

    // Otherwise, do the normal merge.
    return utils.actions.defaultMerge;
  },
});