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/window.c b/src/window.c
index c4448b7..8e53368 100644
--- a/src/window.c
+++ b/src/window.c
@@ -2538,7 +2538,7 @@
 		;
 	    if (ptp == NULL)
 	    {
-		EMSG2(_(e_intern2), "win_close_othertab()");
+		internal_error("win_close_othertab()");
 		return;
 	    }
 	    ptp->tp_next = tp->tp_next;