Switched to non-null assertion for consistency

Author: jvuoti

src/core/queriesObserver.ts

@@ -82,7 +82,7 @@ export class QueriesObserver extends Subscribable<QueriesObserverListener> {
     )
     const matchingObservers = defaultedQueryOptions
       .map(options => {
-        const match = prevObserversMap[options.queryHash ?? '']
+        const match = prevObserversMap[options.queryHash!]
         if (match != null) {
           match.setOptions(options, notifyOptions)
           return match
@@ -119,7 +119,7 @@ export class QueriesObserver extends Subscribable<QueriesObserverListener> {
       .forEach(observer => {
         newObservers.push(observer)
         newResult.push(observer.getCurrentResult())
-        newObserversMap[observer.options.queryHash ?? ''] = observer
+        newObserversMap[observer.options.queryHash!] = observer
       })
 
     return {