patch 8.2.2887: crash when passing null string to fullcommand()

Problem:    Crash when passing null string to fullcommand().
Solution:   Check for NULL pointer. (closes #8256)
diff --git a/src/version.c b/src/version.c
index 4eced11..a6ab4cf 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2887,
+/**/
     2886,
 /**/
     2885,