apply the same NaN/inf fallback in the FigureWidget serializer

_py_to_js sends 1-D float arrays to the frontend as binary buffers
that become typed arrays as well, so a FigureWidget hits the same
stacking reset. Send arrays with non-finite values as lists with null
instead, and turn bare non-finite floats into null too, which also
keeps jupyter_client from falling back to its non-compliant JSON path
for them.

Author: Belagum

plotly/serializers.py

@@ -1,3 +1,5 @@
+import math
+
 from .basedatatypes import Undefined
 from .optional_imports import get_module
 
@@ -38,6 +40,11 @@ def _py_to_js(v, widget_manager):
     # Handle numpy array
     # ------------------
     elif np is not None and isinstance(v, np.ndarray):
+        # NaN/inf can't go out as JSON and plotly.js does not clean them out
+        # of typed arrays, so send them as null like the JSON encoders do
+        if v.dtype.kind == "f" and not np.isfinite(v).all():
+            return np.where(np.isfinite(v), v.astype(object), None).tolist()
+
         # Convert 1D numpy arrays with numeric types to memoryviews with
         # datatype and shape metadata.
         if (
@@ -53,6 +60,11 @@ def _py_to_js(v, widget_manager):
             # Convert all other numpy arrays to lists
             return v.tolist()
 
+    # Handle non-finite floats
+    # ------------------------
+    elif isinstance(v, float) and not math.isfinite(v):
+        return None
+
     # Handle Undefined
     # ----------------
     if v is Undefined:

tests/test_optional/test_graph_objs/test_b64_non_finite.py

@@ -8,6 +8,7 @@
 import plotly.graph_objects as go
 import plotly.io as pio
 from _plotly_utils.utils import to_typed_array_spec
+from plotly.serializers import _py_to_js
 
 try:
     import orjson  # noqa: F401
@@ -73,3 +74,23 @@ def test_to_typed_array_spec_finite():
         "dtype": "f8",
         "bdata": "AAAAAAAA8D8AAAAAAAAAQA==",
     }
+
+
+def test_widget_serializer_non_finite():
+    assert _py_to_js(np.array([1.0, np.nan, np.inf]), None) == [1.0, None, None]
+    assert _py_to_js(np.array([[1.0, np.nan], [2.0, 3.0]]), None) == [
+        [1.0, None],
+        [2.0, 3.0],
+    ]
+    assert _py_to_js({"y": [1.0, float("nan"), -float("inf")]}, None) == {
+        "y": [1.0, None, None]
+    }
+
+
+def test_widget_serializer_finite_array_as_buffer():
+    v = np.array([1.0, 2.0])
+
+    result = _py_to_js(v, None)
+    assert result["dtype"] == "float64"
+    assert result["shape"] == (2,)
+    assert bytes(result["buffer"]) == v.tobytes()