[feature request] more contextual info customMerge about deepmerge

[RebeccaStevens]

This should hopefully do what you want (completely untested):

const result = deepmerge(targetObj, sourceObj, {
  customMerge: (key) => (targetCurrLvl, sourceCurrLvl, options) => {
    if ('objNeedingCustomMerge' in targetCurrLvl[key]) {
      return sourceCurrLvl[key];
    }
    return deepmerge(targetCurrLvl, sourceCurrLvl, options);
  },
});

[tlouisse]

Ah, I see, since the fallback function is deepmerge again (https://github.com/TehShrike/deepmerge/blob/master/index.js#L24)
Thanks! 👍

I also noticed this merge request implements the exact thing requested above, so will wait for that as well: https://github.com/TehShrike/deepmerge/pull/228/files#diff-e727e4bdf3657fd1d798edcd6b099d6e092f8573cba266154583a746bba0f346R64