Fix empty result view when switching between queries

When updating to React 18, we removed the loading step from the updating
of the state of the result view since React would batch the updates
anyway. However, this caused a bug where the result view would be empty
when switching between queries. This is because the result view would
retain the old selected result set name. This would not happen
previously because React would re-render the view at least once, which
would cause the result view to be unmounted and re-created.

This fixes it by resetting the selected result set if we can't find the
result set in the new result sets.

Author: koesie10

extensions/ql-vscode/src/view/results/result-tables.tsx

@@ -139,6 +139,31 @@ export class ResultTables extends React.Component<
     };
   }
 
+  componentDidUpdate(
+    prevProps: Readonly<ResultTablesProps>,
+    prevState: Readonly<ResultTablesState>,
+    snapshot?: any,
+  ) {
+    const resultSetExists =
+      this.props.parsedResultSets.resultSetNames.some(
+        (v) => this.state.selectedTable === v,
+      ) ||
+      this.getResultSets().some(
+        (v) => this.state.selectedTable === v.schema.name,
+      );
+
+    // If the selected result set does not exist, select the default result set.
+    if (!resultSetExists) {
+      const selectedTable =
+        this.props.parsedResultSets.selectedTable ||
+        getDefaultResultSet(this.getResultSets());
+      this.setState({
+        selectedTable,
+        selectedPage: `${this.props.parsedResultSets.pageNumber + 1}`,
+      });
+    }
+  }
+
   untoggleProblemsView() {
     this.setState({
       problemsViewSelected: false,