The test case below generates many spurious error messages. In the beta of 2.047, they have references to type _error. Now that there is a distinct error type, it is straightforward to eliminate them all.

Most occur in expression.c. For example, all the checkXXX() functions should start with:

    if (type == Type::terror)
        return new ErrorExp();

Likewise cases such as:
void BinExp::incompatibleTypes()
{
+    if (e1->type == Type::terror || e2->type == Type::terror)
+        return;

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TEST CASES
--------------

void error_message_tests()
{
    int x = y * 1;
    x = 4 + y;
    int *p = *y;
    x = y++;
    x = 7 - y;
    x = y[3];
    x = ++y;
    x =  y ? 2 : 3;
    x = null[y];
    x = p[y..y];
    y += y;
    x = y/1; // and where the heck did those two divs by 0 come from????
    x = y ~ y;
    x ~= y;
    x = !y;
    x = 3 in y;
    x = y is 2;
    x =  y ^^ 2;
    x ^^= y;
}