fix

anonymous function has not set hashkey, and then should not be searched
in plpgsql_check_HashTable. Anonymous block should be always marked as
unchecked. Fix crash #175

expected/plpgsql_check_passive.out

@@ -353,3 +353,9 @@ end;
 $$ language plpgsql;
 call proc_test();
 drop procedure proc_test();
+-- should not to crash
+set plpgsql_check.mode = 'fresh_start';
+do $$
+begin
+end;
+$$;

expected/plpgsql_check_passive_1.out

@@ -350,3 +350,9 @@ end;
 $$ language plpgsql;
 call proc_test();
 drop procedure proc_test();
+-- should not to crash
+set plpgsql_check.mode = 'fresh_start';
+do $$
+begin
+end;
+$$;

sql/plpgsql_check_passive.sql

@@ -325,3 +325,10 @@ $$ language plpgsql;
 call proc_test();
 
 drop procedure proc_test();
+
+-- should not to crash
+set plpgsql_check.mode = 'fresh_start';
+do $$
+begin
+end;
+$$;

src/check_function.c

@@ -1375,6 +1375,9 @@ plpgsql_check_is_checked(PLpgSQL_function *func)
 {
 	plpgsql_check_HashEnt *hentry;
 
+	if (!func->fn_hashkey)
+		return false;
+
 	hentry = (plpgsql_check_HashEnt *) hash_search(plpgsql_check_HashTable,
 											 (void *) func->fn_hashkey,
 											 HASH_FIND,