Ensure that an AVIF has a ftyp box, and based on ftyp, has other appropriate toplevel boxes present as well

src/read.c

diff --git a/src/read.c b/src/read.c
index 7780f47..632c97e 100644
--- a/src/read.c
+++ b/src/read.c
@@ -2317,6 +2317,12 @@
             return AVIF_RESULT_OK;
         }
     }
+    if (!ftypSeen) {
+        return AVIF_RESULT_INVALID_FTYP;
+    }
+    if ((needsMeta && !metaSeen) || (needsMoov && !moovSeen)) {
+        return AVIF_RESULT_TRUNCATED_DATA;
+    }
     return AVIF_RESULT_OK;
 }