c++: Fix tsubst ICE with invalid code [PR97993, PR97187]

c++: Fix tsubst ICE with invalid code [PR97993, PR97187]

I had a strong sense of deja vu when looking into this, and no wonder,
since this is almost identical to c++/95728.

Since r11-423 tsubst_copy_and_build/TREE_LIST uses tsubst_tree_list
instead of open coding it.  While the latter could return an error
node wrapped in a TREE_LIST, the former can return a naked error node.

That broke in tsubst_copy_and_build/NEW_EXPR, because we were accessing
TREE_VALUE of an error node.

gcc/cp/ChangeLog:

	PR c++/97187
	PR c++/97993
	* pt.c (tsubst_copy_and_build) <case NEW_EXPR>: Return error_mark_node
	if init is erroneous.

gcc/testsuite/ChangeLog:

	PR c++/97187
	PR c++/97993
	* g++.dg/eh/crash2.C: New test.
	* g++.dg/template/crash132.C: New test.