fix(imperative): fix error message for tensors with intbx data type

GitOrigin-RevId: cbb42f8127

imperative/python/src/numpy_dtypes_intbx.cpp

@@ -24,7 +24,7 @@ template <size_t N>
 struct LowBitType {
     static_assert(N < 8, "low bit only supports less than 8 bits");
     static int npy_typenum;
-    //! numerical value (-3, -1, 1, 3)
+    //! allowed numerical value: odd numbers between (-max_value, max_value)
     int8_t value;
 
     struct PyObj;
@@ -32,16 +32,17 @@ struct LowBitType {
 
     const static int32_t max_value = (1 << N) - 1;
 
-    //! check whether val is (-3, -1, 1, 3) and set python error
+    //! check whether val is odd and between (-max_value, max_value) and set python error
     static bool check_value_set_err(int val) {
         int t = val + max_value;
         if ((t & 1) || t < 0 || t > (max_value << 1)) {
             PyErr_SetString(
-                    PyExc_ValueError, mgb::ssprintf(
-                                              "low bit dtype number error: "
-                                              "value=%d; allowed {-3, -1, 1, 3}",
-                                              val)
-                                              .c_str());
+                    PyExc_ValueError,
+                    mgb::ssprintf(
+                            "low bit dtype number error: "
+                            "value=%d; allowed values are odd numbers between [%d,%d]",
+                            val, -max_value, max_value)
+                            .c_str());
             return false;
         }