Fix exception when using funcs and take another approach to escape assembly name

[manodasanW]

• We were previously checking the nested expression to get the parameters. This typically worked before unless it is a func and there was a nested invocation. Fixed to not use the nested ones to get parameters.
• We previously tried to escape any invalid characters from the assembly name. Given that seems to actually be trickier, change the approach to escape anything not on our valid list.