Remove condition that I dont remember why it exists (#27836)

test/core/end2end/fuzzers/api_fuzzer.cc

@@ -444,9 +444,6 @@ class Call : public std::enable_shared_from_this<Call> {
     auto self = shared_from_this();
     return MakeValidator([self, has_ops](bool) {
       --self->pending_ops_;
-      if ((has_ops & (1u << GRPC_OP_RECV_MESSAGE)) && self->call_closed_) {
-        GPR_ASSERT(self->recv_message_ == nullptr);
-      }
       if ((has_ops & (1u << GRPC_OP_RECV_MESSAGE) &&
            self->recv_message_ != nullptr)) {
         grpc_byte_buffer_destroy(self->recv_message_);

test/core/end2end/fuzzers/api_fuzzer_corpus/validator-fail

@@ -0,0 +1,67 @@
+actions {
+  create_server {
+  }
+}
+actions {
+  create_channel {
+    target: "dns:server"
+  }
+}
+actions {
+  create_call {
+    method {
+      value: "/foo"
+    }
+    timeout: 1000000000
+  }
+}
+actions {
+  request_call {
+  }
+}
+actions {
+  queue_batch {
+    operations {
+      send_initial_metadata {
+      }
+    }
+    operations {
+      send_message {
+      }
+    }
+  }
+}
+actions {
+  change_active_call {
+  }
+}
+actions {
+  advance_time: 10000000
+}
+actions {
+  advance_time: 10000000
+}
+actions {
+  poll_cq {
+  }
+}
+actions {
+  queue_batch {
+    operations {
+      receive_message {
+      }
+    }
+  }
+}
+actions {
+  queue_batch {
+    operations {
+      send_close_from_client {
+      }
+    }
+    operations {
+      receive_close_on_server {
+      }
+    }
+  }
+}