Fix out-of-range compiler crash for nested tuple assignment involving

outer unary tuple

test/libsolidity/syntaxTests/tupleAssignments/empty_tuple_assignment.sol

@@ -0,0 +1,35 @@
+function f() pure {
+    ((, ())) = (1, 3);
+}
+
+function g() pure {
+    ((, ((, ())))) = (1, 3);
+}
+
+function t() pure returns (int, int) {
+    return (4, 5);
+}
+
+function h() pure {
+    ((, ())) = t();
+}
+
+function ff() pure {
+    ((((, ())) , )) = ((1, 2), 3);
+}
+
+function fg() pure {
+    (((, ())) , ) = ((1, 2), 3);
+}
+
+// ----
+// TypeError 5547: (28-30): Empty tuple on the left hand side.
+// TypeError 7407: (35-41): Type tuple(int_const 1,int_const 3) is not implicitly convertible to expected type tuple(,tuple()).
+// TypeError 5547: (78-80): Empty tuple on the left hand side.
+// TypeError 7407: (87-93): Type tuple(int_const 1,int_const 3) is not implicitly convertible to expected type tuple(,tuple(,tuple())).
+// TypeError 5547: (187-189): Empty tuple on the left hand side.
+// TypeError 7407: (194-197): Type tuple(int256,int256) is not implicitly convertible to expected type tuple(,tuple()).
+// TypeError 5547: (233-235): Empty tuple on the left hand side.
+// TypeError 7407: (245-256): Type tuple(tuple(int_const 1,int_const 2),int_const 3) is not implicitly convertible to expected type tuple(tuple(,tuple()),).
+// TypeError 5547: (291-293): Empty tuple on the left hand side.
+// TypeError 7407: (302-313): Type tuple(tuple(int_const 1,int_const 2),int_const 3) is not implicitly convertible to expected type tuple(tuple(,tuple()),).

test/libsolidity/syntaxTests/tupleAssignments/fixed_byte_array_assignment_in_tuple.sol

@@ -0,0 +1,7 @@
+contract A {
+    function f() pure public {
+        bytes1 b;
+        bytes1 a;
+        (((, , b))) = (1, 2, a);
+    }
+}