MDEV-35604: SIGSEGV in filter_query_type | log_statement_ex / auditing

Take into account that filter_query_type can get empty query after
skip_set_statement run on incorrect query.

mysql-test/suite/plugins/r/server_audit_pwd_mask.result

@@ -30,4 +30,13 @@ DROP USER u2;
 set global server_audit_logging=off;
 UNINSTALL PLUGIN ed25519;
 UNINSTALL PLUGIN server_audit;
+#
+# MDEV-35604: SIGSEGV in filter_query_type | log_statement_ex / auditing
+#
+INSTALL PLUGIN server_audit SONAME 'server_audit';
+SET GLOBAL server_audit_logging=ON;
+SET STATEMENT max_error_count=1 SELECT 1;
+ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'SELECT 1' at line 1
+SET GLOBAL server_audit_logging=OFF;
+UNINSTALL SONAME 'server_audit';
 # end of 10.5 tests

mysql-test/suite/plugins/t/server_audit_pwd_mask.test

@@ -56,4 +56,20 @@ UNINSTALL PLUGIN ed25519;
 UNINSTALL PLUGIN server_audit;
 --enable_warnings
 
+--echo #
+--echo # MDEV-35604: SIGSEGV in filter_query_type | log_statement_ex / auditing
+--echo #
+
+INSTALL PLUGIN server_audit SONAME 'server_audit';
+SET GLOBAL server_audit_logging=ON;
+
+--ERROR ER_PARSE_ERROR
+SET STATEMENT max_error_count=1 SELECT 1;
+
+# Cleanup
+SET GLOBAL server_audit_logging=OFF;
+--disable_warnings
+UNINSTALL SONAME 'server_audit';
+--enable_warnings
+
 --echo # end of 10.5 tests

plugin/server_audit/server_audit.c

@@ -1765,6 +1765,8 @@ static int filter_query_type(const char *query, struct sa_keyword *kwd)
   char fword[MAX_KEYWORD + 1], nword[MAX_KEYWORD + 1];
   int len, nlen= 0;
   const struct sa_keyword *l_keywords;
+  if (!query)
+    return SQLCOM_NOTHING;
 
   while (*query && (is_space(*query) || *query == '(' || *query == '/'))
   {