fix: handle None in catalog contstructor (#18)

CHANGELOG.md

@@ -4,6 +4,8 @@ All notable changes to this project will be documented in this file.
 
 ## [Unreleased]
 
+-   Fixes a crash caused by ODBC drivers that return non-standard data from a call to `cursor.tables()` ([tconbeer/harlequin#780](https://github.com/tconbeer/harlequin/issues/780) - thank you [@khalid-talakshi](https://github.com/khalid-talakshi)!).
+
 ## [0.3.0] - 2025-02-25
 
 -   The Data Catalog now displays all databases on the connected server, not just the currently-connected database ([tconbeer/harlequin#415](https://github.com/tconbeer/harlequin/discussions/415)).

src/harlequin_odbc/adapter.py

@@ -148,12 +148,19 @@ class HarlequinOdbcConnection(HarlequinConnection):
         cur = self.aux_conn.cursor()
         catalog: dict[str, dict[str, list[tuple[str, str]]]] = {}
         for db_name, schema_name, rel_name, rel_type, *_ in cur.tables(catalog="%"):
+            if db_name is None:
+                continue
             if db_name not in catalog:
-                catalog[db_name] = {schema_name: [(rel_name, rel_type)]}
-            elif schema_name not in catalog[db_name]:
-                catalog[db_name][schema_name] = [(rel_name, rel_type)]
-            else:
-                catalog[db_name][schema_name].append((rel_name, rel_type))
+                catalog[db_name] = dict()
+
+            if schema_name is None:
+                continue
+            if schema_name not in catalog[db_name]:
+                catalog[db_name][schema_name] = list()
+
+            if rel_name is not None:
+                catalog[db_name][schema_name].append((rel_name, rel_type or ""))
+
         return catalog
 
     def _list_columns_in_relation(