patch 8.0.0074
Problem:    Cannot make Vim fail on an internal error.
Solution:   Add IEMSG() and IEMSG2(). (Domenique Pelle)  Avoid reporting an
            internal error without mentioning where.
diff --git a/src/if_cscope.c b/src/if_cscope.c
index 9e7a362..ce6b87f 100644
--- a/src/if_cscope.c
+++ b/src/if_cscope.c
@@ -1792,7 +1792,7 @@
 	cs_print_tags_priv(mp, cp, cnt);
 	break;
     default:	/* should not reach here */
-	(void)EMSG(_("E570: fatal error in cs_manage_matches"));
+	IEMSG(_("E570: fatal error in cs_manage_matches"));
 	return NULL;
     }