Gcontract indicating that variable was not found

[felixholub]

What would you like gtools to add or change (and why)?
When using -gcontract- with a variable which is not defined, the error is uninformative:

. sysuse auto, clear
(1978 Automobile Data)

. gcontract color
Malformed call: 'color'
Syntax: [+|-]varname [[+|-]varname ...]
r(111);

A specific message would be more useful.

Please include a specific suggestion
Return Stata's typical variable color not found

[mcaceresb]

Up in develop.

. qui gtools, upgrade branch(develop)

. sysuse auto, clear
(1978 Automobile Data)

. gcontract color
Variable color not found
r(111);

. gcontract color foreign tires
Variables not found: color tires
r(111);

[felixholub]

Awesone!