test(errors): add unit test for 1364 schema mismatch error

Covers the fix from 308a7f2 — verifies that MariaDB error 1364
is classified as database_schema and the field name is extracted
into a readable message.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/unit/test_unit_errors.py

@@ -41,6 +41,22 @@ def test_null_error_handling():
     else:
         print("❌ Null error check FAILED.")
 
+def test_1364_schema_mismatch():
+    print("\n--- Testing 1364 Schema Mismatch ---")
+    raw = "(MySQLdb.OperationalError) (1364, \"Field 'account' doesn't have a default value\")"
+    formatted = format_db_error(raw)
+    print(f"Raw: {raw}")
+    print(f"Formatted: {formatted}")
+
+    if (formatted.category == "database_schema"
+            and formatted.code == 1364
+            and "account" in formatted.message
+            and "NOT NULL" in formatted.message):
+        print("✅ 1364 schema mismatch handled correctly.")
+    else:
+        print("❌ 1364 schema mismatch check FAILED.")
+
 if __name__ == "__main__":
     test_error_formatting()
     test_null_error_handling()
+    test_1364_schema_mismatch()