Refactor/login (#4583)

lib/src/command/login.dart

diff --git a/lib/src/command/login.dart b/lib/src/command/login.dart
index 0a505b6..695c638 100644
--- a/lib/src/command/login.dart
+++ b/lib/src/command/login.dart
@@ -24,30 +24,28 @@
   @override
   Future<void> runProtected() async {
     final credentials = oauth2.loadCredentials();
+    final userInfo = await _retrieveUserInfo();
+
     if (credentials == null) {
-      final userInfo = await _retrieveUserInfo();
       if (userInfo == null) {
         log.warning(
-          'Could not retrieve your user-details.\n'
-          'You might have to run `$topLevelProgram pub logout` '
-          'to delete your credentials and try again.',
+          'Could not retrieve your user details.\n'
+          'Run `$topLevelProgram pub logout` to delete credentials and try '
+          'again.',
         );
       } else {
         log.message('You are now logged in as $userInfo');
       }
     } else {
-      final userInfo = await _retrieveUserInfo();
       if (userInfo == null) {
         log.warning(
-          'Your credentials seems broken.\n'
-          'Run `$topLevelProgram pub logout` '
-          'to delete your credentials and try again.',
+          'Your credentials seem to be broken.\n'
+          'Run `$topLevelProgram pub logout` to delete credentials and try '
+          'again.',
         );
+      } else {
+        log.message('You are already logged in as $userInfo');
       }
-      log.warning(
-        'You are already logged in as $userInfo\n'
-        'Run `$topLevelProgram pub logout` to log out and try again.',
-      );
     }
   }
 
@@ -55,12 +53,23 @@
     return await oauth2.withClient((client) async {
       final discovery = await oauth2.fetchOidcDiscoveryDocument();
       final userInfoEndpoint = discovery['userinfo_endpoint'];
+
       if (userInfoEndpoint is! String) {
-        log.fine('Bad discovery document. userinfo_endpoint not a String');
+        log.fine('''
+        Invalid discovery document: userinfo_endpoint is not a String
+        ''');
+
         return null;
       }
+
       final userInfoRequest = await client.get(Uri.parse(userInfoEndpoint));
-      if (userInfoRequest.statusCode != 200) return null;
+      if (userInfoRequest.statusCode != 200) {
+        log.fine('''
+        Failed to fetch user info: HTTP ${userInfoRequest.statusCode}
+        ''');
+        return null;
+      }
+
       try {
         switch (json.decode(userInfoRequest.body)) {
           case {'name': final String? name, 'email': final String email}:
@@ -68,15 +77,15 @@
           case {'email': final String email}:
             return _UserInfo(name: null, email: email);
           default:
-            log.fine(
-              'Bad response from $userInfoEndpoint: ${userInfoRequest.body}',
-            );
+            log.fine('''
+            Bad response from $userInfoEndpoint: ${userInfoRequest.body}
+            ''');
             return null;
         }
       } on FormatException catch (e) {
-        log.fine(
-          'Bad response from $userInfoEndpoint ($e): ${userInfoRequest.body}',
-        );
+        log.fine('''
+        Failed to decode user info: $e\nResponse: ${userInfoRequest.body}
+        ''');
         return null;
       }
     });