fix lint warnings (issue 2541) (#2551)

* Lint: fix some errcheck #2541

* Lint: fix passing structcheck #2541

* Lint: update fix structcheck #2541

* Lint: fix errcheck for basicauth, browse, fastcgi_test #2541

* Lint: fix errcheck for browse, fastcgi_test, fcgiclient, fcgiclient_test #2541

* Lint: fix errcheck for responsefilter_test, fcgilient_test #2541

* Lint: fix errcheck for header_test #2541

* Lint: update errcheck for fcgiclient_test #2541

* Lint: fix errcheck for server, header_test, fastcgi_test, https_test, recorder_test #2541

* Lint: fix errcheck for tplcontext, vhosttrie_test, internal_test, handler_test #2541

* Lint: fix errcheck for log_test, markdown mholt#2541

* Lint: fix errcheck for policy, body_test, proxy_test #2541

* Lint: fix errcheck for on multiple packages #2541

- reverseproxy
- reverseproxy_test
- upstream
- upstream_test
- body_test

* Lint: fix errcheck in multiple packages mholt#2541
- handler_test
- redirect_test
- requestid_test
- rewrite_test
- fileserver_test

* Lint: fix errcheck in multiple packages mholt#2541

- websocket
- setup
- collection
- redirect_test
- templates_test

* Lint: fix errcheck in logger test #2541

run goimports against #2551
- lexer_test
- log_test
- markdown

* Update caddyhttp/httpserver/logger_test.go

Co-Authored-By: Inconnu08 <taufiqrx8@gmail.com>

* Update log_test.go

* Lint: fix scope in logger_test #2541

* remove redundant err check in logger_test #2541

* fix alias in logger_test #2541

* fix import for format #2541

* refactor variable names and error check #2541

caddyhttp/httpserver/tplcontext.go

@@ -19,6 +19,7 @@ import (
 	"crypto/rand"
 	"fmt"
 	"io/ioutil"
+	"log"
 	mathrand "math/rand"
 	"net"
 	"net/http"
@@ -420,7 +421,9 @@ func (c Context) RandomString(minLen, maxLen int) string {
 	// secureRandomBytes returns a number of bytes using crypto/rand.
 	secureRandomBytes := func(numBytes int) []byte {
 		randomBytes := make([]byte, numBytes)
-		rand.Read(randomBytes)
+		if _, err := rand.Read(randomBytes); err != nil {
+			log.Println("[ERROR] failed to read bytes: ", err)
+		}
 		return randomBytes
 	}