Work around single-frame image case

Author: hackermd

src/metadata.js

@@ -22,7 +22,10 @@ function formatImageMetadata(metadata) {
   const sharedFunctionalGroupsSequence = metadata['52009229']['Value'][0];
   const pixelMeasuresSequence = sharedFunctionalGroupsSequence['00289110']['Value'][0];
   const pixelSpacing = pixelMeasuresSequence['00280030']['Value'];
-  const numberOfFrames = Number(metadata['00280008']['Value'][0]);
+  let numberOfFrames = 1;
+  if ('00280008' in metadata) {
+    numberOfFrames = Number(metadata['00280008']['Value'][0]);
+  }
 
   /*
    * The values "TILED_SPARSE" and "TILED_FULL" were introduced in the 2018