fix: issue #3840 (#3846)

core/mapping/unmarshaler.go

@@ -626,11 +626,11 @@ func (u *Unmarshaler) processFieldPrimitiveWithJSONNumber(fieldType reflect.Type
 		}
 
 		// if value is a pointer, we need to check overflow with the pointer's value.
-		overflowValidator := value
+		derefedValue := value
-		if overflowValidator.Type().Kind() == reflect.Ptr {
+		for derefedValue.Type().Kind() == reflect.Ptr {
-			overflowValidator = overflowValidator.Elem()
+			derefedValue = derefedValue.Elem()
 		}
-		if overflowValidator.OverflowFloat(fValue) {
+		if derefedValue.CanFloat() && derefedValue.OverflowFloat(fValue) {
 			return fmt.Errorf("parsing %q as float32: value out of range", v.String())
 		}
 

core/mapping/unmarshaler_test.go

@@ -1343,6 +1343,7 @@ func TestUnmarshalNullableSlice(t *testing.T) {
 }
 
 func TestUnmarshalWithFloatPtr(t *testing.T) {
+	t.Run("*float32", func(t *testing.T) {
 		var v struct {
 			WeightFloat32 *float32 `key:"weightFloat32,optional"`
 		}
@@ -1353,6 +1354,20 @@ func TestUnmarshalWithFloatPtr(t *testing.T) {
 		if assert.NoError(t, UnmarshalKey(m, &v)) {
 			assert.Equal(t, float32(3.2), *v.WeightFloat32)
 		}
+	})
+
+	t.Run("**float32", func(t *testing.T) {
+		var v struct {
+			WeightFloat32 **float32 `key:"weightFloat32,optional"`
+		}
+		m := map[string]any{
+			"weightFloat32": json.Number("3.2"),
+		}
+
+		if assert.NoError(t, UnmarshalKey(m, &v)) {
+			assert.Equal(t, float32(3.2), **v.WeightFloat32)
+		}
+	})
 }
 
 func TestUnmarshalIntSlice(t *testing.T) {