Initialize prevFirstChunk to 0 to avoid incorrectly-flagged warning

src/read.c

diff --git a/src/read.c b/src/read.c
index d0f7a9a..ed18cd3 100644
--- a/src/read.c
+++ b/src/read.c
@@ -1848,7 +1848,7 @@
 
     uint32_t entryCount;
     CHECK(avifROStreamReadU32(&s, &entryCount)); // unsigned int(32) entry_count;
-    uint32_t prevFirstChunk;
+    uint32_t prevFirstChunk = 0;
     for (uint32_t i = 0; i < entryCount; ++i) {
         avifSampleTableSampleToChunk * sampleToChunk = (avifSampleTableSampleToChunk *)avifArrayPushPtr(&sampleTable->sampleToChunks);
         CHECK(avifROStreamReadU32(&s, &sampleToChunk->firstChunk));             // unsigned int(32) first_chunk;