fix: when reporting error, report on stderr; since stdout is used for program output
fix: when reporting error, report on stderr; since stdout is used for program output

go-easygen/easygen,suntong/easygen,suntong/easygen,suntong001/easygen,go-easygen/easygen,suntong/easygen,go-easygen/easygen,suntong001/easygen,suntong001/easygen