fix(handleRef): handle null ref correctly (#487)

Author: layershifter

src/lib/handleRef.ts

@@ -20,7 +20,7 @@ const handleRef = <N>(ref: React.Ref<N>, node: N) => {
     return
   }
 
-  if (typeof ref === 'object') {
+  if (ref !== null && typeof ref === 'object') {
     // @ts-ignore The `current` property is defined as readonly, however it's a valid way because
     // `ref` is a mutable object
     ref.current = node

test/specs/lib/handleRef-test.ts

@@ -18,6 +18,14 @@ describe('handleRef', () => {
     expect(ref).toBeCalledWith(node)
   })
 
+  it('does not do anything when "ref" is null', () => {
+    const node = document.createElement('div')
+
+    expect(() => {
+      handleRef(null, node)
+    }).not.toThrowError()
+  })
+
   it('assigns to "current" when "ref" is object', () => {
     const ref = React.createRef<HTMLDivElement>()
     const node = document.createElement('div')