Allow inline root sequence data

Auspice does not attempt to fetch any sidecar file until the main JSON
has been fetched, so it makes sense to avoid attempting to fetch the
root-sequence JSON when it is present in the main dataset JSON.

src/actions/loadData.js

@@ -299,7 +299,7 @@ Dataset.prototype.fetchSidecars = async function fetchSidecars() {
       .catch((reason) => Promise.resolve(reason))
   }
 
-  if (!this.rootSequence) {
+  if (!mainJson.root_sequence && !this.rootSequence) {
     // Note that the browser may log a GET error if the above 404s
     this.rootSequence = fetchJSON(this.apiCalls.rootSequence)
       .catch((reason) => Promise.resolve(reason))

src/actions/recomputeReduxState.js

@@ -733,6 +733,11 @@ const createMetadataStateFromJSON = (json) => {
   if (json.meta.panels) {
     metadata.panels = json.meta.panels;
   }
+  if (json.root_sequence) {
+    /* A dataset may set the root sequence inline (i.e. within the main dataset JSON), which
+    we capture here. Alternatively it may be a sidecar JSON file */
+    metadata.rootSequence = json.root_sequence;
+  }
   if (json.meta.display_defaults) {
     metadata.displayDefaults = {};
     const jsonKeyToAuspiceKey = {