Fix exception message

Author: mdboom

src/_backend_agg.cpp

@@ -2408,7 +2408,7 @@ RendererAgg::tostring_rgba_minimized(const Py::Tuple& args)
         data = PyBytes_FromStringAndSize(NULL, newsize);
         if (data == NULL)
         {
-            throw Py::MemoryError("RendererAgg::tostring_minimized could not allocate memory");
+            throw Py::MemoryError("RendererAgg::tostring_rgba_minimized could not allocate memory");
         }
         dst = (unsigned int *)PyBytes_AsString(data);
 
@@ -2424,7 +2424,7 @@ RendererAgg::tostring_rgba_minimized(const Py::Tuple& args)
         data = PyBytes_FromStringAndSize(NULL, 0);
         if (data == NULL)
         {
-            throw Py::MemoryError("RendererAgg::tostring_minimized could not allocate memory");
+            throw Py::MemoryError("RendererAgg::tostring_rgba_minimized could not allocate memory");
         }
     }