enhanced awk error codes for more consistency

qse/regress/awk/lang-050.awk

@@ -0,0 +1,8 @@
+# When a is assigned 20, a points to a scalar value.
+# The second line turns it to a map if FLEXMAP is on.
+# It is prohibited and results in an error if FLEXMAP is off.
+BEGIN {
+	a=20; 
+	a[10]=30;
+	for (i in a) print i, a[i];
+}