[Fix] Fix several issues preventing gemma3n LoRA support. (#8776)

python/sglang/srt/lora/lora_manager.py

@@ -386,6 +386,13 @@ class LoRAManager:
         else:
             self.target_modules = set()
             for config in self.configs.values():
+                if not isinstance(config.target_modules, list):
+                    raise ValueError(
+                        f"SGLang currently only supports inferring LoRA target modules when a list of "
+                        "suffixes is provided in `target_modules` field of PEFT config. Please explicitly "
+                        "specify `--lora-target-modules` during server startup. You can specify `all` to "
+                        "enable all support modules types. "
+                    )
                 self.target_modules.update(config.target_modules)
 
         if max_lora_rank is not None: