Ensure pthread_join succeeded before returning true

src/tiff/tiffread.c

@@ -644,12 +644,17 @@ internal bool read_strips(TiffReader *reader) {
     }
   }
 
+  bool image_loaded = true;
+
   for (u64 i = 0; i < reader->img.strip_count; ++i) {
-    pthread_join(threads[i], NULL);
+    if (pthread_join(threads[i], NULL) != 0) {
+      image_loaded = false;
+    }
+
     fclose(args[i].fp);
   }
 
-  return true;
+  return image_loaded;
 }
 
 internal void *read_strip(void *arg) {