patch 8.1.1491: when skipping over code a function call may cause trouble

Problem:    When skipping over code after an exception was thrown expression
            evaluation is aborted after a function call. (Ingo Karkat)
Solution:   Do not fail if not executing the expression. (closes #4507)
diff --git a/src/eval.c b/src/eval.c
index abb3b40..c86d0a6 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -4592,7 +4592,7 @@
 		/* Stop the expression evaluation when immediately
 		 * aborting on error, or when an interrupt occurred or
 		 * an exception was thrown but not caught. */
-		if (aborting())
+		if (evaluate && aborting())
 		{
 		    if (ret == OK)
 			clear_tv(rettv);