dayjs through error for null and empty values

**Describe the bug**
Migrating from moment js to dayjs, Facing many issues... Really getting irritated about the behavior of dayjs... I am working on the antd time picker, its showing Invalid Value except for the static time string...

**Expected behavior**
A clear and concise description of what you expected to happen.

**Information**
- Day.js Version [e.g. v1.0.0]
- OS: [e.g. iOS]
- Browser [e.g. chrome 62]
- Time zone: [e.g. GMT-07:00 DST (Pacific Daylight Time)]

Start by reproducing the reported Invalid Value behavior in the antd time picker with null and empty values while migrating from moment.js to Day.js. Collect the missing Day.js version, operating system, browser, and time zone details, then define the expected handling before identifying the relevant source and tests; no repository files or tests are named in the issue.

Written by the indexing model from the issue text.