fix: nullabe column query

Author: juleswritescode

crates/pgt_completions/src/providers/columns.rs

@@ -20,7 +20,7 @@ pub fn complete_columns<'a>(ctx: &CompletionContext<'a>, builder: &mut Completio
             description: format!("Table: {}.{}", col.schema_name, col.table_name),
             kind: CompletionItemKind::Column,
             completion_text: None,
-            detail: Some(col.type_name.to_string()),
+            detail: col.type_name.as_ref().map(|t| t.to_string()),
         };
 
         // autocomplete with the alias in a join clause if we find one

crates/pgt_schema_cache/src/columns.rs

@@ -48,7 +48,7 @@ pub struct Column {
 
     pub schema_name: String,
     pub type_id: i64,
-    pub type_name: String,
+    pub type_name: Option<String>,
     pub is_nullable: bool,
 
     pub is_primary_key: bool,

crates/pgt_schema_cache/src/queries/columns.sql

@@ -55,7 +55,7 @@ from
   left join pg_catalog.pg_type tps on tps.oid = atts.atttypid
 where
   -- system columns, such as `cmax` or `tableoid`, have negative `attnum`s
-  atts.attnum >= 0
+  atts.attnum >= 0 and atts.atttypid != null
 order by
   schema_name desc,
   table_name,