fix(file-detail): show snackbar crash

Signed-off-by: alperozturk96 <alper_ozturk@proton.me>

Author: alperozturk96

app/src/main/java/com/owncloud/android/ui/fragment/FileDetailSharingFragment.java

@@ -186,7 +186,10 @@ private void fetchSharees() {
             return Unit.INSTANCE;
         }, () -> {
             showShareContainer();
-            DisplayUtils.showSnackMessage(getView(), R.string.error_fetching_sharees);
+            final var view = getView();
+            if (view != null) {
+                DisplayUtils.showSnackMessage(view, R.string.error_fetching_sharees);
+            }
             return Unit.INSTANCE;
         });
     }
@@ -411,7 +414,10 @@ public void copyInternalLink() {
         OwnCloudAccount account = accountManager.getCurrentOwnCloudAccount();
 
         if (account == null) {
-            DisplayUtils.showSnackMessage(getView(), getString(R.string.could_not_retrieve_url));
+            final var view = getView();
+            if (view != null) {
+                DisplayUtils.showSnackMessage(view, getString(R.string.could_not_retrieve_url));
+            }
             return;
         }
 
@@ -575,7 +581,10 @@ public void refreshSharesFromDB() {
         }
 
         if (internalShareeListAdapter == null) {
-            DisplayUtils.showSnackMessage(getView(), getString(R.string.could_not_retrieve_shares));
+            final var view = getView();
+            if (view != null) {
+                DisplayUtils.showSnackMessage(view, getString(R.string.could_not_retrieve_shares));
+            }
             return;
         }
 
@@ -728,7 +737,10 @@ public void unShare(OCShare share) {
                 fileDataStorageManager.updateFileEntity(entity);
             }
         } else {
-            DisplayUtils.showSnackMessage(getView(), getString(R.string.failed_update_ui));
+            final var view = getView();
+            if (view != null) {
+                DisplayUtils.showSnackMessage(view, getString(R.string.failed_update_ui));
+            }
         }
     }