Bug: Crash when `VALUES("xxx");`; unsupported exception may should be handled.

[jamhus-tao]

BusTub crashed immediately when input VALUES("xxx");.
Such as follow：

bustub> VALUES ('123');
+--------------+
| __values#0.0 |
+--------------+
| 123          |
+--------------+
bustub> VALUES ("123");
AddressSanitizer:DEADLYSIGNAL
=================================================================
==15583==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000008 (pc 0x5634f19e280d bp 0x7ffc933d1290 sp 0x7ffc933d1270 T0)

which is securely handled on BustTub Web Shell like this:

bustub> VALUES ("123");
unsupported TableReferenceType

But SELECT "xxx"; can be handled.

bustub> SELECT "123";
Message :: unsupported TableReferenceType
unsupported TableReferenceType

---

The following information maybe useful to locate the problem:

VALUE("xxx"); was parsed as:

PGList(VALUES("xxx"))
     \
    PGList(("xxx"))
        \
       PGNode(("xxx"))
           \
     PGColumnRef("xxx")

And for SELECT "xxx";

PGSelectStmt(SELECT "xxx")
     \
    PGList("xxx")
        \
       PGResTarget("xxx")
           \
     PGColumnRef("xxx")

They step in the same funtion src/binder/bind_select.cpp:Binder::BindColumnRef but VALUE has no binder.scope_ (nullptr).

Thus, VALUE("xxx") takes runtime error on src/binder/bind_select.cpp:501.