Implement unimplemented error for getDefaultBlossomServerUrl and improve MIME type detection in ImageUtils

Author: codeswot

lib/config/providers/active_account_provider.dart

@@ -55,7 +55,8 @@ class DefaultWnUtils implements WnUtils {
 
   @override
   Future<String> getDefaultBlossomServerUrl() {
-    return getDefaultBlossomServerUrl();
+    // TODO: Replace with the actual implementation (e.g., read from settings).
+    throw UnimplementedError('getDefaultBlossomServerUrl not implemented');
   }
 }
 

lib/utils/image_utils.dart

@@ -9,15 +9,21 @@ class ImageUtils {
   static Future<String?> getMimeTypeFromPath(String filePath) async {
     try {
       final file = File(filePath);
-      if (!file.existsSync()) {
-        _logger.warning('File does not exist: $filePath, defaulting to image/jpeg');
+      final fileExists = file.existsSync();
+      if (!fileExists) {
+        _logger.warning('File does not exist: $filePath');
         return null;
       }
-
-      final mimeType = lookupMimeType(filePath);
+      List<int>? headerBytes;
+      try {
+        headerBytes = await file.openRead(0, 12).first;
+      } catch (_) {
+        // best-effort; fall back to extension-only detection
+      }
+      final mimeType = lookupMimeType(filePath, headerBytes: headerBytes);
       return mimeType;
-    } catch (e) {
-      _logger.severe('Error reading file for MIME type detection: $filePath, error: $e');
+    } catch (e, st) {
+      _logger.severe('Error reading file for MIME type detection: $filePath', e, st);
       return null;
     }
   }