CLN: de-duplicate IntervalArray validators (#36653)

Author: jbrockmendel

pandas/core/arrays/interval.py

@@ -852,15 +852,15 @@ def _validate_fill_value(self, value):
  return self._validate_scalar(value)
 
  def _validate_fillna_value(self, value):
- if not isinstance(value, Interval):
+ # This mirrors Datetimelike._validate_fill_value
+ try:
+ return self._validate_scalar(value)
+ except ValueError as err:
  msg = (
  "'IntervalArray.fillna' only supports filling with a "
  f"scalar 'pandas.Interval'. Got a '{type(value).__name__}' instead."
  )
- raise TypeError(msg)
-
- self._check_closed_matches(value, name="value")
- return value.left, value.right
+ raise TypeError(msg) from err
 
  def _validate_insert_value(self, value):
  return self._validate_scalar(value)
@@ -887,14 +887,7 @@ def _validate_setitem_value(self, value):
  value_left, value_right = value.left, value.right
 
  else:
- try:
- # list-like of intervals
- array = IntervalArray(value)
- value_left, value_right = array.left, array.right
- except TypeError as err:
- # wrong type: not interval or NA
- msg = f"'value' should be an interval type, got {type(value)} instead."
- raise TypeError(msg) from err
+ return self._validate_listlike(value)
 
  if needs_float_conversion:
  raise ValueError("Cannot set float NaN to integer-backed IntervalArray")