adding unique MetadataRetrivalError class for identifying metadata errors and passing to handler

Author: NikkiBytes

src/utils/metakg/metakg_errors.py

@@ -0,0 +1,16 @@
+class MetadataRetrievalError(Exception):
+    """Custom exception for metadata retrieval failures."""
+    
+    def __init__(self, status_code, message):
+        self.status_code = status_code
+        self.message = message
+        super().__init__(f"MetadataRetrievalError {status_code}: {message}")
+
+    def to_dict(self):
+        """Return error details in JSON-like dictionary format."""
+        return {
+            "code": self.status_code,
+            "success": False,
+            "error": "Metadata Retrieval Error",
+            "details": str(self)
+        }