less code duplication

todo.txt

@@ -31,7 +31,8 @@
 TODO
 
 - bugs
-    editing SC <-> Plant connections at runtime doesn't seem to work
+    (*) editing SC <-> Plant connections at runtime doesn't seem to work
+    (*) non-determinism error highlights only one of enabled transitions
 
 - maybe support:
     - explicit order of:
@@ -64,6 +65,10 @@ TODO
     - show insert mode also next to cursor
     - plot plant signals
 
+    - show error when states partially overlap?
+        useful when accidentally pasting the same data multiple times
+            (otherwise, you can't see that you have multiple states)
+
 - performance:
     maybe try this for rendering the execution trace:
         https://legacy.reactjs.org/docs/optimizing-performance.html#virtualize-long-lists