Is osu.ppy.sh Safe?

My antvirus detected a threat in the game files, and the file type was a "DLL". From what looks like the "download" of the site where you download the game "OSU" was infected by a virus in a file (DLL) that according to my research on the type of file "DLL" the sites said is fine common these types of files contain viruses, the file is named: (bass.dll) which according to my father who is a programmer, he said he has two answers for why the game's installation file has a virus, (1) first option or a hacker put a virus in the "download" of the site where the game "osu" would be downloaded (from what I understood from my father's explanation) or (2) second option in which he (virus) was posted by the website developers, which is what I least want to believe because the game is amazing and seems to have a really cool community. So that's it I just wanted to leave it up so the developers know and solve the problem if they are not the ones who put the virus on purpose. (Make it clear that this is the official website of the game it is only infected by an accidental virus coming from an external hacker or on purpose of the website developers themselves.)