appearance: fixed can't create ThemeObject after theme added

tower: https://tower.im/projects/8f19f0bf0e754f0b82ef2c24bc230973/todos/0da4e517559c482086b5c3b88782af77/#93d801a14f1c4b0fa783e0e871942f07
Change-Id: Ib522bf765efb09515fcfaf5729db4550da9e7ae7