Fix crash on invalid utf8 in decrypted events

src/Olm.cpp

@@ -1048,6 +1048,7 @@ decryptEvent(const MegolmSessionIndex &index,
                 return {DecryptionErrorCode::DecryptionFailed, e.what(), std::nullopt};
         }
 
+        try {
                 // Add missing fields for the event.
                 json body                = json::parse(msg_str);
                 body["event_id"]         = event.event_id;
@@ -1059,13 +1060,12 @@ decryptEvent(const MegolmSessionIndex &index,
                 mtx::common::add_relations(body["content"], event.content.relations);
 
                 mtx::events::collections::TimelineEvent te;
-        try {
                 mtx::events::collections::from_json(body, te);
+
+                return {std::nullopt, std::nullopt, std::move(te.data)};
         } catch (std::exception &e) {
                 return {DecryptionErrorCode::ParsingFailed, e.what(), std::nullopt};
         }
-
-        return {std::nullopt, std::nullopt, std::move(te.data)};
 }
 
 crypto::Trust