Check errors in many places

Admittedly, in some places just document the fact that we ignore error
return values, 'cause we don't know what to do with it.  At least, the
linter is happy.

htpasswd.go

@@ -88,7 +88,6 @@ func (h *HtpasswdFile) Reload() error {
 	if err != nil {
 		return err
 	}
-	defer r.Close()
 
 	cr := csv.NewReader(r)
 	cr.Comma = ':'
@@ -97,6 +96,7 @@ func (h *HtpasswdFile) Reload() error {
 
 	records, err := cr.ReadAll()
 	if err != nil {
+		_ = r.Close()
 		return err
 	}
 	users := make(map[string]string)
@@ -108,6 +108,8 @@ func (h *HtpasswdFile) Reload() error {
 	h.mutex.Lock()
 	h.Users = users
 	h.mutex.Unlock()
+
+	_ = r.Close()
 	return nil
 }
 
@@ -160,7 +162,7 @@ func (h *HtpasswdFile) Validate(user string, password string) bool {
 	}
 	if realPassword[:5] == "{SHA}" {
 		d := sha1.New()
-		d.Write([]byte(password))
+		_, _ = d.Write([]byte(password))
 		if realPassword[5:] == base64.StdEncoding.EncodeToString(d.Sum(nil)) {
 			return true
 		}