From Bloomberg, the source used by Zerohedge:

Spanish police are ready to arrest Catalan President Carles Puigdemont immediately if he declares independence in the regional parliament, according to two people familiar with the government’s plans.

I don´t think that can be considered a reliable source. And none of the main local media are stating that.

Spain is much different than China. With freedom of press, human rights guarantees and the oversight of the European Union. The mobilize of national police in Catalonia is not that big, with 12 000 members in total compared to the 17 000 regional police. Military forces are not mobilized.

Documents confiscated by the police in the home of the vicepresident of Catalonia shows plans of inciting protests and revolts among the civilians in case the Spanish government does not allow independence.

https://politica.elpais.com/politica/2017/10/09/actualidad/1507569660_552707.html

Nationalism should not be repressed by force. But a referendum without guarantees and a 42% participation, after a political campaign full of lies (they said that international law supports that, they said that companies won´t leave Catalonia and they are already doing that...) cannot legitimize a declaration of independence.

Furthermore, some of the law changes made in Catalonia required the approval by at least 2/3 of the parliament majority according to their local regulations, and they approved them just with simple majority.