Cleanup (#98)

lib/app_sources/fdroid.dart

@@ -1,6 +1,7 @@
 import 'package:html/parser.dart';
 import 'package:http/http.dart';
 import 'package:obtainium/components/generated_form.dart';
+import 'package:obtainium/custom_errors.dart';
 import 'package:obtainium/providers/source_provider.dart';
 
 class FDroid implements AppSource {
@@ -18,7 +19,7 @@ class FDroid implements AppSource {
     RegExp standardUrlRegExA = RegExp('^https?://$host/+packages/+[^/]+');
     match = standardUrlRegExA.firstMatch(url.toLowerCase());
     if (match == null) {
-      throw notValidURL(runtimeType.toString());
+      throw InvalidURLError(runtimeType.toString());
     }
     return url.substring(0, match.end);
   }
@@ -36,7 +37,7 @@ class FDroid implements AppSource {
     if (res.statusCode == 200) {
       var releases = parse(res.body).querySelectorAll('.package-version');
       if (releases.isEmpty) {
-        throw couldNotFindReleases;
+        throw NoReleasesError();
       }
       String? latestVersion = releases[0]
           .querySelector('.package-version-header b')
@@ -45,7 +46,7 @@ class FDroid implements AppSource {
           .sublist(1)
           .join(' ');
       if (latestVersion == null) {
-        throw couldNotFindLatestVersion;
+        throw NoVersionError();
       }
       List<String> apkUrls = releases
           .where((element) =>
@@ -64,11 +65,11 @@ class FDroid implements AppSource {
           .where((element) => element.isNotEmpty)
           .toList();
       if (apkUrls.isEmpty) {
-        throw noAPKFound;
+        throw NoAPKError();
       }
       return APKDetails(latestVersion, apkUrls);
     } else {
-      throw couldNotFindReleases;
+      throw NoReleasesError();
     }
   }