Fix copypasta leading to a memory leak in RGB planes

CHANGELOG.md

diff --git a/CHANGELOG.md b/CHANGELOG.md
index c780724..d76dd92 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -20,6 +20,7 @@
 - Sanity check offsets and sizes in items table before using
 - Bail out of box header advertises an impossible size
 - Ran clang-format on all of src and include
+- Fix copypasta leading to a memory leak in RGB planes
 
 ## [0.2.0] - 2019-06-12
 ### Added

src/avif.c

diff --git a/src/avif.c b/src/avif.c
index 18dc775..c03e845 100644
--- a/src/avif.c
+++ b/src/avif.c
@@ -218,9 +218,9 @@
         avifFree(image->rgbPlanes[AVIF_CHAN_G]);
         image->rgbPlanes[AVIF_CHAN_G] = NULL;
         image->rgbRowBytes[AVIF_CHAN_G] = 0;
-        avifFree(image->rgbPlanes[AVIF_CHAN_G]);
-        image->rgbPlanes[AVIF_CHAN_G] = NULL;
-        image->rgbRowBytes[AVIF_CHAN_G] = 0;
+        avifFree(image->rgbPlanes[AVIF_CHAN_B]);
+        image->rgbPlanes[AVIF_CHAN_B] = NULL;
+        image->rgbRowBytes[AVIF_CHAN_B] = 0;
     }
     if ((planes & AVIF_PLANES_YUV) && (image->yuvFormat != AVIF_PIXEL_FORMAT_NONE)) {
         avifFree(image->yuvPlanes[AVIF_CHAN_Y]);