patch 8.1.0747: map() with a bad expression doesn't give an error

Problem:    map() with a bad expression doesn't give an error. (Ingo Karkat)
Solution:   Check for giving an error message. (closes #3800)
diff --git a/src/version.c b/src/version.c
index 4b21d28..c6b9d5f 100644
--- a/src/version.c
+++ b/src/version.c
@@ -796,6 +796,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    747,
+/**/
     746,
 /**/
     745,