Column auto suggestions don't work if a previous select column has an alias

[sivaraam]

• PGSQL Extension Version: v0.3.0
• VSCode Version: v1.51.1
• OS Version: Windows 10

Steps to Reproduce:

1. Connect to a Postgres instance using the extension.
2. Open a new editor and switch language mode to SQL. Use the following query:

   SELECT tablename,
          schemaname,
   
   FROM pg_catalog.pg_tables;

3. Try to trigger auto-suggestions the third select column in the select query and observe that the suggestions are show as expected.
4. Open a new editor and switch language mode to SQL. Use the following query:

   SELECT tablename,
          schemaname AS "schema",
   
   FROM pg_catalog.pg_tables;

5. Try to trigger auto-suggestions the third select column in the select query and observe that the suggestions are not show as expected. In fact, only the snippet suggestions are shown. Not even the keyword suggestions.

Note

I recently noticed this issue with when using PostgreSQL VS code extension in VS code for which I opened an issue in the extension repository. As there's no response there and I somehow guessed the issue is more relevant to be filed in this repository, I'm filing it here. Let me know if this isn't the right place to report this issue. Thanks.