fix some channels missing 7tv emotes (#444)

* remove bang operator

* handle 7tv emotes that are being processed

Author: tommyxchow

lib/apis/seventv_api.dart

@@ -42,6 +42,7 @@ class SevenTVApi {
         emoteSetId,
         emotes
             .map((emote) => Emote.from7TV(emote, EmoteType.sevenTVChannel))
+            .where((emote) => emote.url.isNotEmpty)
             .toList()
       );
     } else {

lib/models/emotes.dart

@@ -1,3 +1,4 @@
+import 'package:collection/collection.dart';
 import 'package:frosty/constants.dart';
 import 'package:json_annotation/json_annotation.dart';
 
@@ -127,7 +128,7 @@ class EmoteFFZ {
 class Emote7TV {
   final String id;
   final String name;
-  final Emote7TVData? data;
+  final Emote7TVData data;
 
   const Emote7TV(
     this.id,
@@ -267,10 +268,10 @@ class Emote {
   factory Emote.from7TV(Emote7TV emote, EmoteType type) {
     final emoteData = emote.data;
 
-    final url = emoteData!.host.url;
+    final url = emoteData.host.url;
 
-    // Flutter doesn't support AVIF yet.
-    final file = emoteData.host.files.lastWhere(
+    // TODO: Remove if/when Flutter natively supports AVIF.
+    final file = emoteData.host.files.lastWhereOrNull(
       (file) => file.format != 'AVIF',
     );
 
@@ -280,10 +281,10 @@ class Emote {
     return Emote(
       name: emote.name,
       realName: emote.name != emoteData.name ? emoteData.name : null,
-      width: emoteData.host.files.first.width,
-      height: emoteData.host.files.first.height,
+      width: emoteData.host.files.firstOrNull?.width,
+      height: emoteData.host.files.firstOrNull?.height,
       zeroWidth: isZeroWidth,
-      url: 'https:$url/${file.name}',
+      url: file != null ? 'https:$url/${file.name}' : '',
       type: type,
       ownerDisplayName: emoteData.owner?.displayName,
       ownerUsername: emoteData.owner?.username,