fix(data): reject partial and malformed map data

tests/dict_test.c

@@ -3,6 +3,7 @@
 void
 dictionary_candidates(struct ct *t)
 {
+	static char malformed[] = { 'o', 'k', ' ', (char)0x80 };
 	char many[512], item[8];
 	char *p;
 	Dictreq req;
@@ -53,6 +54,11 @@ dictionary_candidates(struct ct *t)
 	CT_EQ_INT(t, 0, scmp(&req.pre, &res.key));
 	checkstr(t, "first capped candidate", "c00", &res.kouho[0]);
 	checkstr(t, "last capped candidate", "c31", &res.kouho[31]);
+	key = mkstr("malformed");
+	hmapset(&lang->dict, &key, malformed, sizeof malformed);
+	req.key = key;
+	dictlookup(&req, &res);
+	CT_EQ_INT(t, 0, res.nkouho);
 cleanup:
 	hmapfree(lang->dict);
 	lang->dict = saved;