Error message is confusing when functions are used incorrectly

[tkutz]

Current behavior:
Error messages for wrong function usage (incorrect types) do not specify which types are expected. Instead it says: Function length cannot be used here: uint32, A

Expected behavior:
State which types are expected for the used function. Also A is confusing.

Related code:

var x : stdlib.int16 = 10;
var y : stdlib.int16 = x.length();

[wegendt-bosch]

The A here refers to a free type variable. I'll try to improve this error message by looking at possible instances.