Wazanator の投稿を引用：

halflife2.fgd will throw errors in Hammers error reporter but you can ignore them. Are you sure it is causing hammer to crash?

I wasn't exactly a hard crash or anything like that; it was that one error I described but multiple times, followed by "-too many errors; aborting."

Setup image[i.gyazo.com] (I renamed the old halflife2.fgd as DONTUSE)
Hammer message[i.gyazo.com]

Also, thank you for explaining fgd files for me, they make a lot more sense now.

I am new to Source mapping, so it's been hard finding solid post-Steampipe help for making Garry's Mod maps. This tool has been a big help! That being said, I am a little curious about this Hammer error that occurs when I load the garrysmod.fgd (and by proxy, halflife2.fgd) included with the Source Multi-Tool:

"File *sourcemultitool-path*\fgd\halflife2.fgd, line 37: 'boolean' is not a valid variable type"
This error occurs on several lines before Hammer decides "nah, too many errors, you dun f'd this up".

As far as I can tell, I don't need halflife2.fgd for GMOD 13 mapping - all I want at the moment are assets from CS:S and EP2 and those fgd files were fine, and compiling and running worked great. What's up with halflife2.fgd? Should I be concerned about this?

EDIT: I copied the halflife2.fgd packaged with Garry's Mod into Source Multi-Tool, and the errors went away. After opening the two halflife2.fgd's in Notepad to spot any differences, I saw that multiple lines were removed and method parameters were altered. What's the reasoning behind this, if you don't mind me asking?