perf:remove isinstance check (#3704)

* remove isinstance check inside bytescodec

* remove isinstance check inside bytescodec

* changelog

Author: d-v-b

changes/3704.misc.md

@@ -0,0 +1 @@
+Remove an expensive `isinstance` check from the bytes codec decoding routine.

src/zarr/codecs/bytes.py

@@ -5,10 +5,8 @@
 from enum import Enum
 from typing import TYPE_CHECKING
 
-import numpy as np
-
 from zarr.abc.codec import ArrayBytesCodec
-from zarr.core.buffer import Buffer, NDArrayLike, NDBuffer
+from zarr.core.buffer import Buffer, NDBuffer
 from zarr.core.common import JSON, parse_enum, parse_named_configuration
 from zarr.core.dtype.common import HasEndianness
 
@@ -72,20 +70,15 @@ async def _decode_single(
         chunk_bytes: Buffer,
         chunk_spec: ArraySpec,
     ) -> NDBuffer:
-        assert isinstance(chunk_bytes, Buffer)
         # TODO: remove endianness enum in favor of literal union
         endian_str = self.endian.value if self.endian is not None else None
         if isinstance(chunk_spec.dtype, HasEndianness):
             dtype = replace(chunk_spec.dtype, endianness=endian_str).to_native_dtype()  # type: ignore[call-arg]
         else:
             dtype = chunk_spec.dtype.to_native_dtype()
         as_array_like = chunk_bytes.as_array_like()
-        if isinstance(as_array_like, NDArrayLike):
-            as_nd_array_like = as_array_like
-        else:
-            as_nd_array_like = np.asanyarray(as_array_like)
         chunk_array = chunk_spec.prototype.nd_buffer.from_ndarray_like(
-            as_nd_array_like.view(dtype=dtype)
+            as_array_like.view(dtype=dtype)  # type: ignore[attr-defined]
         )
 
         # ensure correct chunk shape