MDEV-34782 SIGSEGV in handler::update_global_table_stats in close_thread_table()

Handler statistics did not take into account that it could not be fully
initialized in the table.

Author: montywi

mysql-test/main/userstat.result

@@ -287,3 +287,17 @@ test	t1	a	8	1
 drop table t1;
 set global userstat=@save_userstat;
 # End of 11.5 tests
+#
+# MDEV-34782 SIGSEGV in handler::update_global_table_stats in
+# close_thread_table()
+#
+CREATE TABLE t1 (a CHAR(1));
+HANDLER t1 OPEN;
+INSERT INTO t1 VALUES (1);
+HANDLER t1 READ NEXT;
+a
+1
+SET GLOBAL userstat=1;
+HANDLER t1 close;
+drop table t1;
+SET GLOBAL userstat=@save_userstat;

mysql-test/main/userstat.test

@@ -162,3 +162,17 @@ drop table t1;
 set global userstat=@save_userstat;
 
 --echo # End of 11.5 tests
+
+--echo #
+--echo # MDEV-34782 SIGSEGV in handler::update_global_table_stats in
+--echo # close_thread_table()
+--echo #
+
+CREATE TABLE t1 (a CHAR(1));
+HANDLER t1 OPEN;
+INSERT INTO t1 VALUES (1);
+HANDLER t1 READ NEXT;
+SET GLOBAL userstat=1;
+HANDLER t1 close;
+drop table t1;
+SET GLOBAL userstat=@save_userstat;

sql/handler.cc

@@ -6106,8 +6106,11 @@ void handler::update_global_table_stats()
   table_stats->rows_stats.deleted+=       rows_stats.deleted;
   table_stats->rows_stats.key_read_hit+=  rows_stats.key_read_hit;
   table_stats->rows_stats.key_read_miss+= rows_stats.key_read_miss;
-  table_stats->rows_stats.pages_accessed+= handler_stats->pages_accessed;
-  table_stats->rows_stats.pages_read_count+= handler_stats->pages_read_count;
+  if (handler_stats)
+  {
+    table_stats->rows_stats.pages_accessed+=   handler_stats->pages_accessed;
+    table_stats->rows_stats.pages_read_count+= handler_stats->pages_read_count;
+  }
   changed= rows_stats.updated + rows_stats.inserted + rows_stats.deleted;
   table_stats->rows_changed_x_indexes+= (changed *
                                          (table->s->keys ? table->s->keys :