improved error handling of WEBBPSF_EXT_PATH

webbpsf_ext/__init__.py

@@ -52,17 +52,21 @@ class Conf(_config.ConfigNamespace):
         data_path = tempfile.gettempdir()
     else:
         data_path = os.getenv('WEBBPSF_EXT_PATH')
-        if data_path is None:
+        if (data_path is None) or (data_path == ''):
             print("WARNING: Environment variable $WEBBPSF_EXT_PATH is not set!")
             import webbpsf
             data_path = webbpsf.utils.get_webbpsf_data_path()
             print("  Setting WEBBPSF_EXT_PATH to WEBBPSF_PATH directory:")
             print(f"  {data_path}")
+
+        if (data_path is None) or (data_path == ''): 
+            raise IOError(f"WEBBPSF_EXT_PATH ({data_path}) is not a valid path! Have you set WEBBPSF_EXT_PATH environment variable?")
+
         if not os.path.isdir(data_path):
             try:
                 os.makedirs(data_path)
             except:
-                raise IOError(f"WEBBPSF_EXT_PATH ({data_path}) is not a valid directory path!")
+                raise IOError(f"WEBBPSF_EXT_PATH ({data_path}) cannot be created!")
 
     if '/' not in data_path[-1]: 
         # Make sure there is a '/' at the end of the path name

webbpsf_ext/webbpsf_ext_core.py

@@ -2026,7 +2026,13 @@ def _gen_save_dir(self):
     If the directory doesn't exist, try to create it.
     """
     if self._save_dir is None:
-        base_dir = Path(conf.WEBBPSF_EXT_PATH) / 'psf_coeffs/'
+        wext_data_dir = conf.WEBBPSF_EXT_PATH
+        if (wext_data_dir is None) or (wext_data_dir == '/'):
+            wext_data_dir = os.getenv('WEBBPSF_EXT_PATH')
+        if (wext_data_dir is None) or (wext_data_dir == ''):
+            raise IOError(f"WEBBPSF_EXT_PATH ({wext_data_dir}) is not a valid directory path!")
+
+        base_dir = Path(wext_data_dir) / 'psf_coeffs/'
         # Name to save array of oversampled coefficients
         inst_name = self.name
         save_dir = base_dir / f'{inst_name}/'