Assert the presence of the alpha plane (if necessary) in avifImageYUVAnyToRGBAnySlow()
diff --git a/src/reformat.c b/src/reformat.c
index 8d1dd1b..ea19b98 100644
--- a/src/reformat.c
+++ b/src/reformat.c
@@ -442,6 +442,11 @@
// These are the only supported built-ins
assert((chromaUpsampling == AVIF_CHROMA_UPSAMPLING_BILINEAR) || (chromaUpsampling == AVIF_CHROMA_UPSAMPLING_NEAREST));
+ // If toRGBAlphaMode is active (not no-op), assert that the alpha plane is present. The end of
+ // the avifPrepareReformatState() function should ensure this, but this assert makes it clear
+ // to clang's analyzer.
+ assert((state->toRGBAlphaMode == AVIF_ALPHA_MULTIPLY_MODE_NO_OP) || aPlane);
+
for (uint32_t j = 0; j < image->height; ++j) {
const uint32_t uvJ = j >> state->formatInfo.chromaShiftY;
const uint8_t * ptrY8 = &yPlane[j * yRowBytes];
