fix!: Ensure ArrowTypeString never returns NULL

python/src/nanoarrow/_array.pyx

@@ -143,8 +143,7 @@ cdef class CArrayView:
     @property
     def storage_type(self):
         cdef const char* type_str = ArrowTypeString(self._ptr.storage_type)
-        if type_str != NULL:
-            return type_str.decode('UTF-8')
+        return type_str.decode('UTF-8')
 
     @property
     def layout(self):

python/src/nanoarrow/_schema.pyx

@@ -594,18 +594,12 @@ cdef class CSchemaView:
     @property
     def type(self) -> str:
         cdef const char* type_str = ArrowTypeString(self._schema_view.type)
-        if type_str != NULL:
-            return type_str.decode()
-        else:
-            raise ValueError("ArrowTypeString() returned NULL")
+        return type_str.decode()
 
     @property
     def storage_type(self) -> str:
         cdef const char* type_str = ArrowTypeString(self._schema_view.storage_type)
-        if type_str != NULL:
-            return type_str.decode()
-        else:
-            raise ValueError("ArrowTypeString() returned NULL")
+        return type_str.decode()
 
     @property
     def dictionary_ordered(self) -> Union[bool, None]:

src/nanoarrow/common/inline_types.h

@@ -473,7 +473,7 @@ enum ArrowType {
 /// \brief Get a string value of an enum ArrowType value
 /// \ingroup nanoarrow-utils
 ///
-/// Returns NULL for invalid values for type
+/// Returns "<unknown type identifier>" for invalid values for type
 static inline const char* ArrowTypeString(enum ArrowType type);
 
 static inline const char* ArrowTypeString(enum ArrowType type) {
@@ -569,7 +569,7 @@ static inline const char* ArrowTypeString(enum ArrowType type) {
     case NANOARROW_TYPE_LARGE_LIST_VIEW:
       return "large_list_view";
     default:
-      return NULL;
+      return "<unknown type identifier>";
   }
 }