Function getFamilyTypeById

getFamilyTypeById(layerId, thematicId): JLAYER_THEMATIC_FAMILY_TYPES
JMap.Layer.Thematic.getFamilyTypeById

Returns the family of the specified layer thematic
Parameters
- layerId: JId
  The JMap layer id
- thematicId: JId
  The thematic id
Returns JLAYER_THEMATIC_FAMILY_TYPES
Throws
Error if layer or thematic is not found, or if an invalid param is provided

Example
```
// returns the family of thematic id=3 of layer id=7
let family = JMap.Layer.Thematic.getFamilyTypeById(
   layerId: 7,
   thematicId: 3
 )
console.log(family)
// "Classification"
```