Why this matters
The bug. io.Copy returns both bytes-written and error. Discarding the error means partial-write failures (disk full, network drop, permission revoked mid-write) propagate as 'success' all the way to the user.
The fix. Capture the error, return it.
Even more correct. Also verify f.Sync() and check f.Close()'s return value — close itself can fail and is the *last* chance to learn the file isn't durable.
Review heuristic
Every catch block should answer two questions in the diff or in a comment: which specific exceptions am I handling, and what do I do with the rest? catch (e) {} is the smoking gun; except: pass is its Python cousin.
External reference: CWE-248: Uncaught Exception.