Update uncertainty.py - fix heteroscedastic loss clamping

uncertainty.py

@@ -408,9 +408,9 @@ class HeteroscedasticHead(nn.Module):
         Args:
             hidden_states: (B, L, d_model)
         Returns:
-            log_var: (B, L, n_outputs) — predicted log-variance per head
+            log_var: (B, L, n_outputs) — predicted log-variance per head, clamped to [-5, 5]
         """
-        return self.log_var_head(hidden_states)
+        return torch.clamp(self.log_var_head(hidden_states), -5.0, 5.0)
 
 
 # ============================================================