Reading the Western press, the People's Republic of China (from hereon China) regularly threatens military brimstone and hellfire if the Republic of China (Taiwan) dares to declare independence. However, an acquaintance recently pointed out that if you read the actual wording of the threats, they are always couched in terms of fending off an attack on Taiwan, and if you see anything claiming otherwise, it's probably misquoting or editorializing. In other words, they're not directed against Taiwan itself, but against unspecified "invaders", "anyone who splits Taiwan from China", etc. A few recent examples, emphasis mine:

“We have the determination and ability to mount a painful direct
attack against any invaders who would wreck unification of the
motherland, and would show no mercy.” -NYT

"If anyone dares to split Taiwan from China, the Chinese army will definitely not hesitate to start a war no matter the cost” -Al Jazeera

This old article from 2000 describes China's position as follows, but provides no direct link:

Previously, China suggested that force would be used only in the event
of a foreign invasion of the island, or a declaration of independence
by Taiwan. But now the threat has been extended to apply if Taipei
indefinitely maintains its refusal to hold talks on unifying the two
governments, under Beijing's leadership.

So: has China ever unambiguously stated that it will invade if Taiwan declares independence? Bonus points for citations to sources either in Chinese, or from a Chinese government publication in English.