MDEV-36758: always release ctx in mhnsw_delete_all

Fixes leak of shared context.

Author: iMineLink

mysql-test/main/vector2.result

@@ -453,4 +453,12 @@ select * from t;
 v
 1111
 drop table t;
+#
+# MDEV-36758 - LeakSanitizer errors in MHNSW_Share::alloc_node after DML on empty table with vector key
+#
+create table t (v vector(1) not null, vector(v)) engine=myisam;
+delete from t;
+insert into t values (0x31313131);
+delete from t;
+drop table t;
 # End of 11.8 tests

mysql-test/main/vector2.test

@@ -331,4 +331,13 @@ set statement sql_mode='' for alter table t modify v vector(1);
 select * from t;
 drop table t;
 
+--echo #
+--echo # MDEV-36758 - LeakSanitizer errors in MHNSW_Share::alloc_node after DML on empty table with vector key
+--echo #
+create table t (v vector(1) not null, vector(v)) engine=myisam;
+delete from t;
+insert into t values (0x31313131);
+delete from t;
+drop table t;
+
 --echo # End of 11.8 tests

sql/vector_mhnsw.cc

@@ -1546,9 +1546,9 @@ int mhnsw_delete_all(TABLE *table, KEY *keyinfo, bool truncate)
   if (!MHNSW_Share::acquire(&ctx, table, true))
   {
     ctx->reset(table->s);
-    ctx->release(table);
   }
 
+  ctx->release(table);
   return 0;
 }