Update extensions/ql-vscode/src/log-insights/join-order.ts

Co-authored-by: Andrew Eisenberg <aeisenberg@github.com>

Author: Dave Bartolomeo

extensions/ql-vscode/src/log-insights/join-order.ts

@@ -248,7 +248,7 @@ class JoinOrderScanner implements EvaluationLogScanner {
             const key = makeKey(
               event.queryCausingWork,
               predicate,
-              '(' + raReference + ')'
+              `(${raReference})`
             );
             const maxTupleCount = Math.max(...bucket.tupleCounts);
             const resultSize = bucket.resultSize;