add dirm default fix

Author: ali-cetin-4ss

src/waveresponse/_core.py

@@ -2140,6 +2140,9 @@ def dirm(self, degrees=None):
             during instantiation.
         """
 
+        if degrees is None:
+            degrees = self._degrees
+
         dp, sp = self.spectrum1d(axis=0, degrees=False)
 
         d = self._full_range_dir(dp)
@@ -2288,6 +2291,9 @@ def dirm(self, degrees=None):
             during instantiation.
         """
 
+        if degrees is None:
+            degrees = self._degrees
+
         dirm = self._mean_direction(*self.spectrum1d(axis=0, degrees=False))
 
         if degrees: