typo and try_except fix

[madMatchstick]

Fixes for get_var_nbytes() & set_value() required for standalone runs

Changes

• get_var_nbytes(): remove lingering ) in return line
• set_value(): the else block is expected for standalone versions as value passed is of type scalar

Testing

1. run_bmi_unit_test.py
2. run-lstm-with-bmi.py

Todos

• Test in ngen