Bug 1765728 - Handle pre-snapshot events/crashes in Nyx. r=truber

Depends on D143459

Differential Revision: https://phabricator.services.mozilla.com/D144508

tools/fuzzing/nyx/Nyx.cpp

@@ -183,8 +183,6 @@ void Nyx::release(uint32_t iterations) {
 
 void Nyx::handle_event(const char* type, const char* file, int line,
                        const char* reason) {
-  MOZ_RELEASE_ASSERT(mInited);
-
   if (mReplayMode) {
     MOZ_FUZZING_NYX_PRINTF(
         "[Replay Mode] Nyx::handle_event() called: %s at %s:%d : %s\n", type,
@@ -192,7 +190,15 @@ void Nyx::handle_event(const char* type, const char* file, int line,
     return;
   }
 
-  nyx_handle_event(type, file, line, reason);
+  // We can have events such as MOZ_CRASH even before we snapshot.
+  // Output some useful information to make it clear where it happened.
+  MOZ_FUZZING_NYX_PRINTF(
+      "[ERROR] PRE SNAPSHOT Nyx::handle_event() called: %s at %s:%d : %s\n",
+      type, file, line, reason);
+
+  if (mInited) {
+    nyx_handle_event(type, file, line, reason);
+  }
 }
 
 }  // namespace fuzzing