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)

src/eval.c

@@ -4592,7 +4592,7 @@ eval7(
 		/* 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);

src/testdir/test_eval_stuff.vim

@@ -178,3 +178,12 @@ func Test_scriptversion()
   call assert_fails('source Xversionscript', 'E999:')
   call delete('Xversionscript')
 endfunc
+
+" Test fix for issue #4507
+func Test_skip_after_throw()
+  try
+    throw 'something'
+    let x = wincol() || &ts
+  catch /something/
+  endtry
+endfunc

src/version.c

@@ -767,6 +767,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1491,
 /**/
     1490,
 /**/