Fix corruption of skeleton when using CTRL+Rightclick in empty tree (#…

…5385)

* avoid corruption of skeleton in weird case; also ensure that first node of a tree is always selected after creation

* update changelog

CHANGELOG.unreleased.md

@@ -22,6 +22,7 @@ For upgrade instructions, please check the [migration guide](MIGRATIONS.released
 - Fixed a bug where some values in the project list were displayed incorrectly after pausing/unpausing the project. [#5339](https://github.com/scalableminds/webknossos/pull/5339)
 - Fixed that editing a task type would always re-add the default values to the recommended configuration (if enabled). [#5341](https://github.com/scalableminds/webknossos/pull/5341)
 - Fixed a bug where tasks created from existing volume annotations that did not have a specified bounding box were broken. [#5362](https://github.com/scalableminds/webknossos/pull/5361)
+- Fixed a bug which could cause corrupted trees when CTRL+Rightclick was used in an empty tree. [#5385](https://github.com/scalableminds/webknossos/pull/5385)
 - Fixed a bug in Safari which could cause an error message (which is safe to ignore). [#5373](https://github.com/scalableminds/webknossos/pull/5373)
 - Fixed artifacts in screenshots near the dataset border. [#5324](https://github.com/scalableminds/webknossos/pull/5324)
 - Fixed a bug where the page would scroll up unexpectedly when showing various confirm modals. [#5371](https://github.com/scalableminds/webknossos/pull/5371)

frontend/javascripts/oxalis/controller/combinations/skeletontracing_plane_controller.js

@@ -420,8 +420,10 @@ export function setWaypoint(
   const center = state.userConfiguration.centerNewNode && !ctrlIsPressed;
   // Only create a branchpoint if CTRL is pressed. Unless newNodeNewTree is activated (branchpoints make no sense then)
   const branchpoint = ctrlIsPressed && !state.userConfiguration.newNodeNewTree;
-  // Always activate the new node unless CTRL is pressed
-  const activate = !ctrlIsPressed;
+  // Always activate the new node unless CTRL is pressed. If there is no current node,
+  // the new one is still activated regardless of CTRL (otherwise, using CTRL+click in an empty tree multiple times would
+  // not create any edges; see https://github.com/scalableminds/webknossos/issues/5303).
+  const activate = !ctrlIsPressed || activeNodeMaybe.isNothing;
 
   addNode(position, rotation, createNewTree, center, branchpoint, activate);
 }

frontend/javascripts/oxalis/model/reducers/skeletontracing_reducer_helpers.js

@@ -131,6 +131,11 @@ export function createNode(
   const { allowUpdate } = restrictions;
   const activeNodeMaybe = getActiveNodeFromTree(skeletonTracing, tree);
 
+  if (activeNodeMaybe.isNothing && tree.nodes.size() !== 0) {
+    console.error("Couldn't create a node in non-empty tree, because there is no active node.");
+    return Maybe.Nothing();
+  }
+
   if (allowUpdate) {
     // Use the same radius as current active node or revert to default value
     const radius = activeNodeMaybe