Fix raising exception when the model in project dir is not a MLF

Fix missing 'raise' when raising a TVMCException when the 'tvmc run'
finds a model in the project dir but its format is not a MLF, e.g. when
the model is compiled without `--output-format mlf` and the resulting
model is kept in the 'classic' archive format.

This also tries to enhance a bit the message when the exception happens.

python/tvm/driver/tvmc/runner.py

@@ -177,10 +177,8 @@ def drive_run(args):
         path = path / "model.tar"
         if not path.is_file():
             TVMCException(
-                f"Could not find MLF {path} in the specified project dir {path.dirname()}."
+                f"Could not find model (model.tar) in the specified project dir {path.dirname()}."
             )
-        else:
-            print("MLF found, using micro target runner.")
 
         # Check for options unavailable for micro targets.
 
@@ -197,6 +195,8 @@ def drive_run(args):
         if args.profile:
             raise TVMCException("--profile is not supported for micro targets.")
 
+        # Get and check options for micro targets.
+
         options = get_options(args.project_option)
         check_options(options, args.valid_options)
         check_options_choices(options, args.valid_options)
@@ -463,7 +463,7 @@ def run_module(
     micro = False
     if device == "micro":
         if tvmc_package.type != "mlf":
-            TVMCException("--device 'micro' specified but no MLF archive found in PATH.")
+            raise TVMCException(f"Model {tvmc_package.package_path} is not a MLF archive.")
 
         micro = True
         project_dir = os.path.dirname(tvmc_package.package_path)