Object.assign()

The Object.assign() method copies all enumerable own properties from one or more source objects to a target object. It returns the modified target object. Your task is to replicate this functionality.

• If the target is null or undefined, throw a TypeError.
• Only enumerable and own properties should be copied.
• Later source properties overwrite earlier ones if they have the same key.
• The method should return the target object.

Example Inputs & Outputs

customAssign({a: 1}, {b: 2}) → {a: 1, b: 2}  
customAssign({a: 1}, {a: 2, b: 3}) → {a: 2, b: 3}  
customAssign({}, {a: undefined}, {b: null}) → {a: undefined, b: null}  

Constraints & Edge Cases

• target must not be null or undefined
• Only own, enumerable properties of source objects should be copied
• If a source is null or undefined, it should be skipped (not throw an error)
• Must return the modified target object
• Symbol properties should be ignored in this simplified version