TechDraw: Improve and clean up code in some Python classes

src/Mod/TechDraw/App/DrawViewSymbolPyImp.cpp

@@ -45,14 +45,10 @@ PyObject* DrawViewSymbolPy::dumpSymbol(PyObject *args)
 {
     const char* fileSpec;
     if (!PyArg_ParseTuple(args, "s", &fileSpec)) {
-       throw Py::TypeError("** dumpSymbol bad args.");
-    }
-    auto dvs = getDrawViewSymbolPtr();
-    std::string symbolRepr;
-    if (dvs) {
-        symbolRepr = dvs->Symbol.getValue();
+        return nullptr;
     }
 
+    std::string symbolRepr = getDrawViewSymbolPtr()->Symbol.getValue();
     Base::FileInfo fi(fileSpec);
     Base::ofstream outfile;
     outfile.open(fi);
@@ -63,8 +59,10 @@ PyObject* DrawViewSymbolPy::dumpSymbol(PyObject *args)
     } else {
         std::string error = std::string("Can't write ");
         error += fileSpec;
-        throw Py::RuntimeError(error);
+        PyErr_SetString(PyExc_RuntimeError, error.c_str());
+        return nullptr;
     }
+
     Py_Return;
 }