dsl: es must be revised

[masatake]

es is used in readtags for reading S expressions. In some areas, it is broken. I must revise it.

          following place needs to do such checking too:

https://github.com/universal-ctags/ctags/blob/master/dsl/es.c#L2684

Originally posted by @leleliu008 in https://github.com/universal-ctags/ctags/issues/3644#issuecomment-1429539600