Better exception handling, fix README code

astroquery/mast/missions.py

@@ -12,6 +12,7 @@
 from astropy.table import Table
 import astropy.units as u
 import astropy.coordinates as coord
+from requests import JSONDecodeError, RequestException
 
 from astroquery.utils import commons, async_to_sync
 from astroquery.utils.class_or_instance import class_or_instance
@@ -292,8 +293,18 @@ def get_column_list(self):
                 # Create Table with parsed data
                 col_table = Table(rows=rows, names=('name', 'data_type', 'description'))
                 self.columns[self.mission] = col_table
+            except JSONDecodeError as ex:
+                raise JSONDecodeError(f'Failed to decode JSON response while attempting to get column list'
+                                      f' for mission {self.mission}: {ex}')
+            except RequestException as ex:
+                raise ConnectionError(f'Failed to connect to the server while attempting to get column list'
+                                      f' for mission {self.mission}: {ex}')
+            except KeyError as ex:
+                raise KeyError(f'Expected key not found in response data while attempting to get column list'
+                               f' for mission {self.mission}: {ex}')
             except Exception as ex:
-                raise RuntimeError(f'Error occurred while trying to get column list for mission {self.mission}: {ex}')
+                raise RuntimeError(f'An unexpected error occurred while attempting to get column list'
+                                   f' for mission {self.mission}: {ex}')
 
         return self.columns[self.mission]
 

astroquery/mast/tests/data/README.rst

@@ -6,12 +6,11 @@ This directory contains sample data that is used to mock functions in `~astroque
 
 To generate `~astroquery.mast.tests.data.mission_columns.json`, use the following:
 
-.. code-block:: python
+.. doctest-remote-data::
 
     >>> import json
     >>> from astroquery.mast import utils
-
-    >>> params = {'mission': 'hst'}
-    >>> resp = utils._simple_request(f'https://mast.stsci.edu/search/util/api/v0.1/column_list', {'mission': 'hst'})
+    ...
+    >>> resp = utils._simple_request('https://mast.stsci.edu/search/util/api/v0.1/column_list', {'mission': 'hst'})
     >>> with open('mission_columns.json', 'w') as file:
-    >>>     json.dump(resp.json(), file, indent=4)
+    ...     json.dump(resp.json(), file, indent=4)