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/edit.c b/src/edit.c
index 3a0e188..0d9e9d4 100644
--- a/src/edit.c
+++ b/src/edit.c
@@ -2299,7 +2299,7 @@
 	case CTRL_X_EVAL:
 	    return (c == Ctrl_P || c == Ctrl_N);
     }
-    EMSG(_(e_internal));
+    internal_error("vim_is_ctrl_x_key()");
     return FALSE;
 }
 
@@ -5431,7 +5431,7 @@
 	}
 	else
 	{
-	    EMSG2(_(e_intern2), "ins_complete()");
+	    internal_error("ins_complete()");
 	    return FAIL;
 	}