:bug: Fix NPE

kernel/sql/asset_content_query.go

@@ -185,5 +185,8 @@ func queryAssetContent(query string, args ...interface{}) (*sql.Rows, error) {
 	if "" == query {
 		return nil, errors.New("statement is empty")
 	}
+	if nil == assetContentDB {
+		return nil, errors.New("database is nil")
+	}
 	return assetContentDB.Query(query, args...)
 }

kernel/sql/database.go

@@ -1316,6 +1316,9 @@ func queryRow(query string, args ...interface{}) *sql.Row {
 		logging.LogErrorf("statement is empty")
 		return nil
 	}
+	if nil == db {
+		return nil
+	}
 	return db.QueryRow(query, args...)
 }
 
@@ -1324,6 +1327,9 @@ func query(query string, args ...interface{}) (*sql.Rows, error) {
 	if "" == query {
 		return nil, errors.New("statement is empty")
 	}
+	if nil == db {
+		return nil, errors.New("database is nil")
+	}
 	return db.Query(query, args...)
 }
 

kernel/sql/history.go

@@ -72,6 +72,9 @@ func QueryHistory(stmt string) (ret []map[string]interface{}, err error) {
 }
 
 func SelectHistoriesRawStmt(stmt string) (ret []*History) {
+	if nil == historyDB {
+		return
+	}
 	rows, err := historyDB.Query(stmt)
 	if err != nil {
 		logging.LogWarnf("sql query [%s] failed: %s", stmt, err)
@@ -101,6 +104,9 @@ func queryHistory(query string, args ...interface{}) (*sql.Rows, error) {
 	if "" == query {
 		return nil, errors.New("statement is empty")
 	}
+	if nil == historyDB {
+		return nil, errors.New("database is nil")
+	}
 	return historyDB.Query(query, args...)
 }