Fatal error: exception Marshal_tools.Reading_Preamble_Exception

I'm trying to run `hh_client` on a fairly large project that is converted to Hack with `hackificator` (3220 files, 42MB), but it fails throwing a `Marshal_tools.Reading_Preamble_Exception`.

### HHVM Version

3.15.3

### Standalone code, or other way to reproduce the problem

```
$ hh_client
```

### Expected result

`hh_client` reports errors.

### Actual result

```
$ hh_client
For more detailed logs, try `tail -f $(hh_client --monitor-logname) $(hh_client --logname)`
Server launched with the following command:
'/usr/local/bin/hh_server' '-d' '..' '--waiting-client' '5'
Spawned typechecker (child pid=3589)
Logs will go to /tmp/hh_server/...monitor_log
hh_server is busy: [processing] -Error, only read 0 bytes for preamble.
Fatal error: exception Marshal_tools.Reading_Preamble_Exception
```

### Discussion

This is the result of tailing the logs at the same time.

```
$ tail -f $(hh_client --monitor-logname) $(hh_client --logname)
==> /tmp/hh_server/...monitor_log <==
[2016-12-02 16:59:20] Could not load config at /etc/hh.conf, using defaults
[2016-12-02 16:59:20] About to spawn typechecker daemon. Logs will go to /tmp/hh_server/...log

[2016-12-02 16:59:20] Just started typechecker server with pid: 3594.
[2016-12-02 16:59:20] Got request for typechecker. Prior request 0.0 seconds ago

==> /tmp/hh_server/...log <==
[2016-12-02 16:59:20] Version: 965cd8d30670726d88720412c3384225a2da011d Sat Nov 19 08:54:55 2016
[2016-12-02 16:59:20] Could not load config at /etc/hh.conf, using defaults
[2016-12-02 16:59:20] Could not load config at /etc/hh.conf, using defaults
[2016-12-02 16:59:20] Initializing Server (This might take some time)
[2016-12-02 16:59:20] Init id: 0BYRNMs3YK
[2016-12-02 16:59:20] Indexing: 0.024645
[2016-12-02 16:59:23] Heap size: 105277568
[2016-12-02 16:59:23] Parsing: 3.611402
[2016-12-02 16:59:23] Loading mini-state: 0.000034
[2016-12-02 16:59:23] Updating deps: 0.007205
[2016-12-02 16:59:23] Heap size: 108058112
[2016-12-02 16:59:23] Naming: 0.121928
[2016-12-02 16:59:25] Heap size: 133868288
[2016-12-02 16:59:25] Type-decl: 1.828719
[2016-12-02 16:59:25] Finding changed files: 0.000029
[2016-12-02 16:59:33] Heap size: 133990528
[2016-12-02 16:59:33] Type-check: 7.272825
[2016-12-02 16:59:33] Dependency table load factor: 230295 / 262144 (0.88)

==> /tmp/hh_server/...monitor_log <==
[2016-12-02 16:59:34] typechecker signaled with exit code 7
```

If I run `hh_server --check` instead, it works fine (but takes a while).

```
$ hh_server --check .
[2016-12-02 17:04:31] Could not load config at /etc/hh.conf, using defaults
[2016-12-02 17:04:31] Version: 965cd8d30670726d88720412c3384225a2da011d Sat Nov 19 08:54:55 2016
[2016-12-02 17:04:31] Could not load config at /etc/hh.conf, using defaults
[2016-12-02 17:04:31] Could not load config at /etc/hh.conf, using defaults
[2016-12-02 17:04:31] Indexing: 0.007498
[2016-12-02 17:04:33] Heap size: 105277568
[2016-12-02 17:04:33] Parsing: 2.657399
[2016-12-02 17:04:33] Loading mini-state: 0.000022
[2016-12-02 17:04:34] Heap size: 108058112
[2016-12-02 17:04:34] Naming: 0.841094
[2016-12-02 17:05:29] Heap size: 133867968
[2016-12-02 17:05:29] Type-decl: 54.825868
[2016-12-02 17:05:29] Finding changed files: 0.027999
[2016-12-02 17:05:58] Heap size: 133990208
[2016-12-02 17:05:58] Type-check: 29.013689
[2016-12-02 17:05:58] Dependency table load factor: 0 / 262144 (0.00)
[2016-12-02 17:06:01] Hashtable load factor: 146573 / 67108864 (0.00)
[2016-12-02 17:06:01] Waiting for daemon(s) to be ready...
[2016-12-02 17:06:01] Running in check mode

```

How can I debug this?