gh-146092: Fix error handling in _BINARY_OP_ADD_UNICODE opcode (#146117)

Fix also error handling in _BINARY_OP_ADD_FLOAT,
_BINARY_OP_SUBTRACT_FLOAT and _BINARY_OP_MULTIPLY_FLOAT opcodes.
PyStackRef_FromPyObjectSteal() must not be called with a NULL
pointer.

Author: vstinner

Modules/_testinternalcapi/test_cases.c.h

@@ -710,10 +710,11 @@ dummy_func(
             double dres =
                 ((PyFloatObject *)left_o)->ob_fval *
                 ((PyFloatObject *)right_o)->ob_fval;
-            res = PyStackRef_FromPyObjectSteal(PyFloat_FromDouble(dres));
-            if (PyStackRef_IsNull(res)) {
+            PyObject *d = PyFloat_FromDouble(dres);
+            if (d == NULL) {
                 ERROR_NO_POP();
             }
+            res = PyStackRef_FromPyObjectSteal(d);
             l = left;
             r = right;
             INPUTS_DEAD();
@@ -729,10 +730,11 @@ dummy_func(
             double dres =
                 ((PyFloatObject *)left_o)->ob_fval +
                 ((PyFloatObject *)right_o)->ob_fval;
-            res = PyStackRef_FromPyObjectSteal(PyFloat_FromDouble(dres));
-            if (PyStackRef_IsNull(res)) {
+            PyObject *d = PyFloat_FromDouble(dres);
+            if (d == NULL) {
                 ERROR_NO_POP();
             }
+            res = PyStackRef_FromPyObjectSteal(d);
             l = left;
             r = right;
             INPUTS_DEAD();
@@ -748,10 +750,11 @@ dummy_func(
             double dres =
                 ((PyFloatObject *)left_o)->ob_fval -
                 ((PyFloatObject *)right_o)->ob_fval;
-            res = PyStackRef_FromPyObjectSteal(PyFloat_FromDouble(dres));
-            if (PyStackRef_IsNull(res)) {
+            PyObject *d = PyFloat_FromDouble(dres);
+            if (d == NULL) {
                 ERROR_NO_POP();
             }
+            res = PyStackRef_FromPyObjectSteal(d);
             l = left;
             r = right;
             INPUTS_DEAD();
@@ -772,10 +775,10 @@ dummy_func(
 
             STAT_INC(BINARY_OP, hit);
             PyObject *res_o = PyUnicode_Concat(left_o, right_o);
-            res = PyStackRef_FromPyObjectSteal(res_o);
-            if (PyStackRef_IsNull(res)) {
+            if (res_o == NULL) {
                 ERROR_NO_POP();
             }
+            res = PyStackRef_FromPyObjectSteal(res_o);
             l = left;
             r = right;
             INPUTS_DEAD();