add missing error-checking

Author: ngoldbaum

tests/test_pythoncapi_compat_cext.c

@@ -1432,29 +1432,48 @@ test_long_api(PyObject *Py_UNUSED(module), PyObject *Py_UNUSED(args))
     PyLongWriter *writer;
     static PyLongExport long_export;
 
-    writer = PyLongWriter_Create(1, 1, (void**)&digits);
+    writer = PyLongWriter_Create(1, 1, (void **)&digits);
+    if (writer == NULL) {
+        return NULL;
+    }
     PyLongWriter_Discard(writer);
 
-    writer = PyLongWriter_Create(1, 1, (void**)&digits);
+    writer = PyLongWriter_Create(1, 1, (void **)&digits);
+    if (writer == NULL) {
+        return NULL;
+    }
     digits[0] = 123;
     obj = PyLongWriter_Finish(writer);
+    if (obj == NULL) {
+        return NULL;
+    }
 
     check_int(obj, -123);
-    PyLong_Export(obj, &long_export);
+    if (PyLong_Export(obj, &long_export) < 0) {
+        return NULL;
+    }
     assert(long_export.value == -123);
     assert(long_export.digits == NULL);
     PyLong_FreeExport(&long_export);
     Py_DECREF(obj);
 
-    writer = PyLongWriter_Create(0, 5, (void**)&digits);
+    writer = PyLongWriter_Create(0, 5, (void **)&digits);
+    if (writer == NULL) {
+        return NULL;
+    }
     digits[0] = 1;
     digits[1] = 0;
     digits[2] = 0;
     digits[3] = 0;
     digits[4] = 1;
     obj = PyLongWriter_Finish(writer);
+    if (obj == NULL) {
+        return NULL;
+    }
 
-    PyLong_Export(obj, &long_export);
+    if (PyLong_Export(obj, &long_export) < 0) {
+        return NULL;
+    }
     assert(long_export.value == 0);
     digits = (digit*)long_export.digits;
     assert(digits[0] == 1);