refactor(core): improve create_new_session func

[no changelog]

core/src/apps/thp/create_new_session.py

@@ -7,16 +7,22 @@ from trezor.wire.thp import SessionState
 
 
 async def create_new_session(message: ThpCreateNewSession) -> ThpNewSession | Failure:
+    """
+    Creates a new `ThpSession` based on the provided parameters and returns a
+    `ThpNewSession` message containing the new session ID.
+
+    Returns an appropriate `Failure` message if session creation fails.
+    """
+    from trezor.wire import NotInitialized
+    from trezor.wire.thp.session_context import GenericSessionContext
     from trezor.wire.thp.session_manager import create_new_session
 
     from apps.common.seed import derive_and_store_roots
 
     ctx = get_context()
 
-    # Assert that context `ctx` is ManagementSessionContext
-    from trezor.wire.thp.session_context import ManagementSessionContext
-
-    assert isinstance(ctx, ManagementSessionContext)
+    # Assert that context `ctx` is `GenericSessionContext`
+    assert isinstance(ctx, GenericSessionContext)
 
     channel = ctx.channel
 
@@ -30,7 +36,11 @@ async def create_new_session(message: ThpCreateNewSession) -> ThpNewSession | Fa
         return Failure(code=FailureType.DataError, message=e.message)
     except ActionCancelled as e:
         return Failure(code=FailureType.ActionCancelled, message=e.message)
-    # TODO handle other errors
+    except NotInitialized as e:
+        return Failure(code=FailureType.NotInitialized, message=e.message)
+    # TODO handle other errors (`Exception`` when "Cardano icarus secret is already set!"
+    # and `RuntimeError` when accessing storage for mnemonic.get_secret - it actually
+    # happens for locked devices)
 
     new_session.set_session_state(SessionState.ALLOCATED)
     channel.sessions[new_session.session_id] = new_session