try fix seg err v2

Author: NyanFisher

src/msgspec/_core.c

@@ -9663,7 +9663,6 @@ Encoder_init(Encoder *self, PyObject *args, PyObject *kwds)
             PyErr_SetString(PyExc_TypeError, "`decimal_quantize` must be a Decimal");
             return -1;
         }
-        Py_XDECREF(type);
         Py_INCREF(decimal_quantize);
     }
 
@@ -11863,47 +11862,55 @@ quantize_decimal_obj(EncoderState *self, PyObject *obj)
     if (self->decimal_quantize == NULL) {
         return NULL;
     }
- 
+
     PyObject *quantize_method = PyObject_GetAttrString(obj, "quantize");
     if (quantize_method == NULL) {
         return NULL;
     }
 
     // Create rounding constant as string object
     PyObject *rounding_const_obj = NULL;
+    int need_decref_rounding = 0;
     switch (self->decimal_rounding) {
         case ROUND_DEFAULT:
             rounding_const_obj = Py_None;
             break;
         case ROUND_DOWN:
             rounding_const_obj = PyUnicode_InternFromString("ROUND_DOWN");
+            need_decref_rounding = 1;
             break;
         case ROUND_HALF_UP:
             rounding_const_obj = PyUnicode_InternFromString("ROUND_HALF_UP");
+            need_decref_rounding = 1;
             break;
         case ROUND_HALF_EVEN:
             rounding_const_obj = PyUnicode_InternFromString("ROUND_HALF_EVEN");
+            need_decref_rounding = 1;
             break;
         case ROUND_CEILING:
             rounding_const_obj = PyUnicode_InternFromString("ROUND_CEILING");
+            need_decref_rounding = 1;
             break;
         case ROUND_FLOOR:
             rounding_const_obj = PyUnicode_InternFromString("ROUND_FLOOR");
+            need_decref_rounding = 1;
             break;
         case ROUND_UP:
             rounding_const_obj = PyUnicode_InternFromString("ROUND_UP");
+            need_decref_rounding = 1;
             break;
         case ROUND_HALF_DOWN:
             rounding_const_obj = PyUnicode_InternFromString("ROUND_HALF_DOWN");
+            need_decref_rounding = 1;
             break;
         case ROUND_05UP:
             rounding_const_obj = PyUnicode_InternFromString("ROUND_05UP");
+            need_decref_rounding = 1;
             break;
         default:
             rounding_const_obj = NULL;
             break;
     }
-    Py_XINCREF(rounding_const_obj);
 
     if (rounding_const_obj == NULL) {
         Py_DECREF(quantize_method);
@@ -11919,10 +11926,8 @@ quantize_decimal_obj(EncoderState *self, PyObject *obj)
     );
 
     Py_DECREF(quantize_method);
-    Py_XDECREF(rounding_const_obj);
-
-    if (quantized_obj == NULL) {
-        return NULL;
+    if (need_decref_rounding) {
+        Py_DECREF(rounding_const_obj);
     }
 
     return quantized_obj;