signals-react: fix isSignalsAvailable

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

.changeset/tricky-apricots-film.md

@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-signals-react': patch
+---
+
+Fix for `useSignal` returning the inverse value for `isSignalsAvailable`.

plugins/signals-react/src/hooks/useSignal.ts

@@ -46,7 +46,7 @@ export const useSignal = <TMessage extends JsonObject = JsonObject>(
   }, [signals, channel]);
 
   // Can be used to fallback (for example to long polling) if signals are not available in the system
-  const isSignalsAvailable = useMemo(() => !signals, [signals]);
+  const isSignalsAvailable = useMemo(() => !!signals, [signals]);
 
   return { lastSignal, isSignalsAvailable };
 };