From @trevorlitsey on Mon, 17 Jun 2019 19:42:35 GMT

What happened

When deep merging two Maps with the same key name but different value types, no merge is done and the key's value remains unchanged. I would expect the value to be overwritten.

How to reproduce

var objWithObj = Immutable.fromJS({ 
  items: { 
    '1': { 
      id: '1'
    } 
  } 
})
var objWithArray = Immutable.fromJS({ 
  items: [{
    id: '1'
  }] 
})
var mergedObj = ObjWithObj.mergeDeep(objWithArray)

Copied from original issue: immutable-js#1719