fix: Opening HEIC images now throws UnidentifiedImageError

This will allow pillow-avif-plugin to be interoperable with the HEIC
opener in pillow_heif. Fixes #19.

CHANGELOG.rst

@@ -11,12 +11,16 @@ Changelog
   ``save()``).
 * **Fixed**: ``tile_cols`` encoder setting (the ``save()`` method was using
   the value passed to ``tile_rows`` instead)
+* **Fixed**: Attempts to open non-AV1 images in HEIF containers (e.g. HEIC)
+  now raises UnidentifiedImageError, not ValueError. Fixes `#19`_.
 * **CI**: manylinux2014 aarch64 wheels
 * **CI**: bundle libyuv and libsharpyuv
 * **CI**: Python 3.11 wheels
 * **CI**: Update bundled libraries (see table below, changes from previous
   release in bold)
 
+.. _#19: https://github.com/fdintino/pillow-avif-plugin/issues/19
+
 .. table::
 
   ===========  ==========

src/pillow_avif/_avif.c

@@ -125,10 +125,10 @@ normalize_tiles_log2(int value) {
 static PyObject *
 exc_type_for_avif_result(avifResult result) {
     switch (result) {
-        case AVIF_RESULT_INVALID_FTYP:
         case AVIF_RESULT_INVALID_EXIF_PAYLOAD:
         case AVIF_RESULT_INVALID_CODEC_SPECIFIC_OPTION:
             return PyExc_ValueError;
+        case AVIF_RESULT_INVALID_FTYP:
         case AVIF_RESULT_BMFF_PARSE_FAILED:
         case AVIF_RESULT_TRUNCATED_DATA:
         case AVIF_RESULT_NO_CONTENT:

tests/test_file_avif.py

@@ -648,6 +648,11 @@ def test_sequence_dimension_mismatch_check(self, tmp_path):
         with pytest.raises(ValueError):
             frame1.save(temp_file, save_all=True, append_images=[frame2], duration=100)
 
+    def test_heif_raises_unidentified_image_error(self):
+        with pytest.raises(UnidentifiedImageError or IOError):
+            with Image.open("tests/images/rgba10.heif"):
+                pass
+
     @skip_unless_avif_version_gte((0, 9, 0))
     @pytest.mark.parametrize("alpha_premultipled", [False, True])
     def test_alpha_premultiplied_true(self, alpha_premultipled):