Merge pull request nextstrain#1986 from nextstrain/james/display-defaults-optional-bug

[bugfix] datasets without display_defaults

Author: jameshadfield

CHANGELOG.md

@@ -1,7 +1,8 @@
 # Changelog
 
-## version 2.63.0 - 2025/06/02
+* Fixed a bug where datasets without the (optional!) `display_defaults` would crash, which included newick files dragged onto auspice.us. ([#1986](https://github.com/nextstrain/auspice/pull/1986))
 
+## version 2.63.0 - 2025/06/02
 
 * **Streamtrees** are a new visualisation option for displaying phylogenetic trees. They require datasets with labels on internal nodes which we essentially use to partition the nodes of the tree and render each partition as a streamgraph. Such visualisations are useful for conveying relationships between parts of the tree as well as improving performance for very large trees. See the [added documentation](https://docs.nextstrain.org/projects/auspice/en/latest/advanced-functionality/streamtrees.html) for more details. ([#1902](https://github.com/nextstrain/auspice/issues/1902))
 

src/actions/recomputeReduxState.js

@@ -482,7 +482,7 @@ const modifyControlsStateViaTree = (state, tree, treeToo, metadata) => {
   }
 
   state.availableStreamLabelKeys = availableStreamLabelKeys(tree.availableBranchLabels, metadata.streamLabels);
-  if (metadata.displayDefaults.streamLabel) {
+  if (metadata?.displayDefaults?.streamLabel) {
     if (state.availableStreamLabelKeys.includes(metadata.displayDefaults.streamLabel)) {
       state.showStreamTrees = true;
       state.streamTreeBranchLabel = metadata.displayDefaults.streamLabel;