fix(stream): fix get_moa_stream ValueError (#251)

Author: tachyonicClock

src/capymoa/stream/_stream.py

@@ -347,9 +347,9 @@ def next_instance(self) -> _AnyInstance:
     def get_schema(self) -> Schema:
         """Return the schema of the stream."""
 
-    @abstractmethod
     def get_moa_stream(self) -> Optional[InstanceStream]:
         """Get the MOA stream object if it exists."""
+        return None
 
     @abstractmethod
     def restart(self):
@@ -557,9 +557,6 @@ def next_instance(self) -> _AnyInstance:
     def get_schema(self):
         return self.schema
 
-    def get_moa_stream(self):
-        raise ValueError("Not a moa_stream, a numpy read file")
-
     def restart(self):
         self.current_instance_index = 0
 
@@ -927,9 +924,6 @@ def next_instance(self) -> _AnyInstance:
     def get_schema(self):
         return self.schema
 
-    def get_moa_stream(self):
-        raise ValueError("No moa_stream available, this is a CSV")
-
     def restart(self):
         self.total_number_of_lines = 0
         self.n_lines_to_skip = 1 if self.skip_header else 0