* fix QF1011: could omit type *os.File from declaration; it will be inferred from the right-hand side
* fix QF1012: Use fmt.Fprintf(x, ...) instead of x.Write(fmt.Sprintf(...))
* fix QF1001: could apply De Morgan's law
* fix QF1003: could use tagged switch
* fix weakCond: suspicious ; nil check may not be enough, check for len (gocritic)
* fix docStub: silencing go lint doc-comment warnings is unadvised
* fix builtinShadow: shadowing of predeclared identifier: error
* fix importShadow: shadow of imported package
* fix nestingReduce: invert if cond, replace body with , move old body after the statement
* useless-break: useless break in case clause (revive)
* Clear the redundant content in golangci.yaml file