Enforce that NcAttribute.value is always an 0- or 1-D array.

lib/ncdata/_core.py

@@ -503,12 +503,23 @@ def __init__(self, name: str, value):  # noqa: D107
         #: attribute name
         self.name: str = name
         # Attribute values are arraylike, have dtype
-        # TODO: may need to regularise string representations?
-        if not hasattr(value, "dtype"):
-            value = np.asanyarray(value)
         #: attribute value
         self.value: np.ndarray = value
 
+    @property
+    def value(self):  # noqa: D102
+        return self._value
+
+    @value.setter
+    def value(self, value):
+        if not hasattr(value, "dtype"):
+            value = np.asanyarray(value)
+        if value.ndim > 1:
+            raise ValueError(
+                "Attribute value should only be 0- or 1-dimensional."
+            )
+        self._value = value
+
     def as_python_value(self):
         """
         Return the content, but converting any character data to Python strings.

lib/ncdata/utils/_compare_nc_datasets.py

@@ -385,7 +385,7 @@ def getdata(var):
             isnans, isnans2 = (np.isnan(arr) for arr in (flatdata, flatdata2))
             if np.any(isnans) or np.any(isnans2):
                 nandiffs = np.where(isnans != isnans2)[0]
-                if nandiffs:
+                if nandiffs.size > 0:
                     flat_diff_inds += list(nandiffs)
                 anynans = isnans | isnans2
                 flatdata[anynans] = safe_fill_const