db_sqlite: Improve error handling

* avoid dangling PS pointers
* avoid leaking the PS object on NULL "result"

Author: liviuchircu

modules/db_sqlite/dbase.c

@@ -183,6 +183,7 @@ int db_sqlite_query(const db_con_t* _h, const db_key_t* _k, const db_op_t* _op,
 	if (db_sqlite_bind_values(CON_SQLITE_PS(_h), _v, _n) != SQLITE_OK) {
 		LM_ERR("failed to bind values\n");
 		sqlite3_finalize(CON_SQLITE_PS(_h));
+		CON_SQLITE_PS(_h) = NULL;
 		return -1;
 	}
 #endif
@@ -198,8 +199,13 @@ int db_sqlite_query(const db_con_t* _h, const db_key_t* _k, const db_op_t* _op,
 			ret = 0;
 		}
 	}
-	if( ret < 0 && _r ){
-		db_sqlite_free_result_internal(_h,*_r);
+	if( ret < 0 ) {
+		if (_r) {
+			db_sqlite_free_result_internal(_h,*_r);
+		} else if (CON_SQLITE_PS(_h)) {
+			sqlite3_finalize(CON_SQLITE_PS(_h));
+			CON_SQLITE_PS(_h) = NULL;
+		}
 	}
 
 	return ret;
@@ -394,8 +400,13 @@ int db_sqlite_raw_query(const db_con_t* _h, const str* _s, db_res_t** _r)
 			ret = 0;
 		}
 	}
-	if( ret < 0 && _r ){
-		db_sqlite_free_result_internal(_h,*_r);
+	if( ret < 0 ){
+		if (_r) {
+			db_sqlite_free_result_internal(_h,*_r);
+		} else if (CON_SQLITE_PS(_h)) {
+			sqlite3_finalize(CON_SQLITE_PS(_h));
+			CON_SQLITE_PS(_h) = NULL;
+		}
 	}
 
 	return ret;