chore(gopher): simplify file creation error handling

internal/protocol/gopher/gopher.go

@@ -204,11 +204,11 @@ func (p *Protocol) downloadText(ctx context.Context, reader *bufio.Reader, req *
 					return nil, core.NewFileError("failed to create output directory", err)
 				}
 			}
-			var ferr error
-			file, ferr = os.Create(req.Output)
-			if ferr != nil {
-				return nil, core.NewFileError("failed to create output file", ferr)
+			f, err := os.Create(req.Output)
+			if err != nil {
+				return nil, core.NewFileError("failed to create output file", err)
 			}
+			file = f
 			defer file.Close()
 			writer = file
 		}