fix: conditional RNtuple

Signed-off-by: Henry Schreiner <[email protected]>

Author: henryiii

src/uproot_browser/plot.py

@@ -52,7 +52,6 @@ def plot(tree: Any) -> None:
 
 # Simpler in Python 3.11+
 @plot.register(uproot.TBranch)
-@plot.register(uproot.models.RNTuple.RField)
 def plot_branch(tree: uproot.TBranch | uproot.models.RNTuple.RField) -> None:
     """
     Plot a single tree branch.
@@ -71,6 +70,10 @@ def plot_branch(tree: uproot.TBranch | uproot.models.RNTuple.RField) -> None:
     plt.title(make_hist_title(tree, histogram))
 
 
+if hasattr(uproot.models, "RNTuple") and hasattr(uproot.models.RNTuple, "RField"):
+    plot.register(uproot.models.RNTuple.RField)(plot_branch)  # type: ignore[no-untyped-call]
+
+
 @plot.register
 def plot_hist(tree: uproot.behaviors.TH1.Histogram) -> None:
     """

src/uproot_browser/tree.py

@@ -57,9 +57,13 @@ def _(item: uproot.behaviors.TBranch.HasBranches) -> bool:
     return len(item.branches) > 0
 
 
-@is_dir.register
-def _(item: uproot.behaviors.RNTuple.HasFields) -> bool:
-    return len(item.keys()) > 0
+if hasattr(uproot.behaviors, "RNTuple") and hasattr(
+    uproot.behaviors.RNTuple, "HasFields"
+):
+
+    @is_dir.register
+    def _(item: uproot.behaviors.RNTuple.HasFields) -> bool:
+        return len(item.keys()) > 0
 
 
 def get_children(item: Mapping[str, Any]) -> set[str]:
@@ -159,7 +163,6 @@ def _process_item_tfile(
 
 # Python 3.11 can just use `|` directly for register
 @process_item.register(uproot.TTree)
-@process_item.register(uproot.behaviors.RNTuple.RNTuple)
 def _process_item_ttree(
     uproot_object: uproot.TTree | uproot.behaviors.RNTuple.RNTuple,
 ) -> MetaDict:
@@ -178,6 +181,9 @@ def _process_item_ttree(
     )
 
 
+process_item.register(uproot.behaviors.RNTuple.RNTuple)(_process_item_ttree)  # type: ignore[no-untyped-call]
+
+
 @process_item.register
 def _process_item_tbranch(uproot_object: uproot.TBranch) -> MetaDict:
     """