updated for version 7.3.825
Problem:    With Python errors are not always clear.
Solution:   Print the stack trace, unless :silent is used. (ZyX)
diff --git a/src/if_python3.c b/src/if_python3.c
index 5311483..d8f7574 100644
--- a/src/if_python3.c
+++ b/src/if_python3.c
@@ -122,6 +122,7 @@
 # define PyDict_SetItemString py3_PyDict_SetItemString
 # define PyErr_BadArgument py3_PyErr_BadArgument
 # define PyErr_Clear py3_PyErr_Clear
+# define PyErr_PrintEx py3_PyErr_PrintEx
 # define PyErr_NoMemory py3_PyErr_NoMemory
 # define PyErr_Occurred py3_PyErr_Occurred
 # define PyErr_SetNone py3_PyErr_SetNone
@@ -279,6 +280,7 @@
 static void* (*py3_PyMem_Malloc)(size_t);
 static int (*py3_Py_IsInitialized)(void);
 static void (*py3_PyErr_Clear)(void);
+static void (*py3_PyErr_PrintEx)(int);
 static PyObject*(*py3__PyObject_Init)(PyObject *, PyTypeObject *);
 static iternextfunc py3__PyObject_NextNotImplemented;
 static PyObject* py3__Py_NoneStruct;
@@ -403,6 +405,7 @@
     {"_Py_FalseStruct", (PYTHON_PROC*)&py3__Py_FalseStruct},
     {"_Py_TrueStruct", (PYTHON_PROC*)&py3__Py_TrueStruct},
     {"PyErr_Clear", (PYTHON_PROC*)&py3_PyErr_Clear},
+    {"PyErr_PrintEx", (PYTHON_PROC*)&py3_PyErr_PrintEx},
     {"PyObject_Init", (PYTHON_PROC*)&py3__PyObject_Init},
     {"PyModule_AddObject", (PYTHON_PROC*)&py3_PyModule_AddObject},
     {"PyImport_AppendInittab", (PYTHON_PROC*)&py3_PyImport_AppendInittab},
@@ -842,7 +845,11 @@
 	r = PyRun_String(PyBytes_AsString(cmdbytes), Py_eval_input,
 			 globals, globals);
 	if (r == NULL)
+	{
+	    if (PyErr_Occurred() && !msg_silent)
+		PyErr_PrintEx(0);
 	    EMSG(_("E860: Eval did not return a valid python 3 object"));
+	}
 	else
 	{
 	    if (ConvertFromPyObject(r, rettv) == -1)