memory: do not release pointers after emitting a signal

A signal called is allowed to free ourselves, in which case we're not allowed to use this anymore. Only perform the housekeeping of removing stale events before emit, and in registerListener.

src/signal/Signal.cpp

@@ -9,14 +9,10 @@ using namespace Hyprutils::Memory;
 #define WP CWeakPointer
 
 void Hyprutils::Signal::CSignal::emit(std::any data) {
-    bool                             dirty = false;
-
     std::vector<SP<CSignalListener>> listeners;
     for (auto& l : m_vListeners) {
-        if (l.expired()) {
-            dirty = true;
+        if (l.expired())
             continue;
-        }
 
         listeners.emplace_back(l.lock());
     }
@@ -29,10 +25,9 @@ void Hyprutils::Signal::CSignal::emit(std::any data) {
     for (auto& l : listeners) {
         // if there is only one lock, it means the event is only held by the listeners
         // vector and was removed during our iteration
-        if (l.strongRef() == 1) {
-            dirty = true;
+        if (l.strongRef() == 1)
             continue;
-        }
+
         l->emit(data);
     }
 
@@ -43,13 +38,17 @@ void Hyprutils::Signal::CSignal::emit(std::any data) {
     // release SPs
     listeners.clear();
 
-    if (dirty)
-        std::erase_if(m_vListeners, [](const auto& other) { return other.expired(); });
+    // we cannot release any expired refs here as one of the listeners could've removed this object and 
+    // as such we'd be doing a UAF
 }
 
 CHyprSignalListener Hyprutils::Signal::CSignal::registerListener(std::function<void(std::any)> handler) {
     CHyprSignalListener listener = makeShared<CSignalListener>(handler);
     m_vListeners.emplace_back(listener);
+
+    // housekeeping: remove any stale listeners
+    std::erase_if(m_vListeners, [](const auto& other) { return other.expired(); });
+
     return listener;
 }