What steps will reproduce the problem?
1. Install GuildCraft
2. Click on tradeskill links from guild members who don't have GuildCraft installed to add their data to GuildCraft
3. Type /gyp

What is the expected output? What do you see instead?
The GYP window should pop up. Instead I get an error (see below).

What version of the product are you using?
r28beta, the latest version on Curse

Do you have an error log of what happened?
GnomishYellowPages-r28\GnomishYellowPages.lua:1759 GetSpellInfo(): Invalid spell slot

Please provide any additional information below.
The latest GuildCraft version captures tradeskill links from guild members if you click their chat links even if they don't use GuildCraft themselves. Apparently GuildCraft strips their links, i.e. "|cffffd000|Htrade:2550:49:75:3E5C6D:HAAAgABAEAwAAAAQAAAAAAAAAAYAA|h[Cooking]|h|r" becomes "trade:2550:49:75:3E5C6D:HAAAgABAEAwAAAAQAAAAAAAAAAYAA". This causes the string.find call in line 1755 to not match anything, so tradeID is nil and causes the error in line 1759.

Quick solution that fixed the bug for me: Change line 1755 from
local _,_,tradeID,level,bitmap  = string.find(link, "trade:(%d+):(%d+):%d+:[0-9a-fA-F]+:([A-Za-z0-9+/]+)|h")
to
local _,_,tradeID,level,bitmap  = string.find(link, "trade:(%d+):(%d+):%d+:[0-9a-fA-F]+:([A-Za-z0-9+/]+)")
to not expect the traling "|h" control code.