[glom] PyGlomRelatedRecord: Initialize m_document and check it for null.

[Murray Cumming <murrayc src gnome org>]

commit 2be01b1b58c5eb49c9563c4f4e42712ca3cc2ce2
Author: Murray Cumming <murrayc murrayc com>
Date:   Wed Dec 3 08:46:18 2014 +0100

    PyGlomRelatedRecord: Initialize m_document and check it for null.
    
    Found by Coverity Scan.

 glom/libglom/python_embed/py_glom_relatedrecord.cc |   15 +++++++++++++++
 1 files changed, 15 insertions(+), 0 deletions(-)
---
diff --git a/glom/libglom/python_embed/py_glom_relatedrecord.cc 
b/glom/libglom/python_embed/py_glom_relatedrecord.cc
index f4ae40a..053b6f1 100644
--- a/glom/libglom/python_embed/py_glom_relatedrecord.cc
+++ b/glom/libglom/python_embed/py_glom_relatedrecord.cc
@@ -35,6 +35,7 @@ namespace Glom
 {
 
 PyGlomRelatedRecord::PyGlomRelatedRecord()
+: m_document(0)
 {
 }
 
@@ -67,6 +68,13 @@ boost::python::object PyGlomRelatedRecord::getitem(const boost::python::object&
 
   const Glib::ustring related_table = m_relationship->get_to_table();
 
+  if(!m_document)
+  {
+    std::cerr << G_STRFUNC << ": m_document is null. field: " << field_name << ", table:" << 
m_relationship->get_to_table() << std::endl;
+    PyErr_SetString(PyExc_IndexError, "m_document is null");
+    return boost::python::object();
+  }
+
   //Check whether the field exists in the table.
   sharedptr<const Field> field = m_document->get_field(m_relationship->get_to_table(), field_name);
   if(!field)
@@ -153,6 +161,13 @@ boost::python::object PyGlomRelatedRecord::generic_aggregate(const std::string&
 {
   const Glib::ustring related_table = m_relationship->get_to_table();
 
+  if(!m_document)
+  {
+    std::cerr << G_STRFUNC << ": m_document is null. field: " << field_name << ", table:" << related_table 
<< std::endl;
+    PyErr_SetString(PyExc_RuntimeError, "m_document is null");
+    return boost::python::object();
+  }
+
   //Check whether the field exists in the table.
   sharedptr<Field> field = m_document->get_field(m_relationship->get_to_table(), field_name);
   if(!field)