KeyError: 'bst' reported in latex_installed_packages.py

[dnaihao]

Since my sublime cannot fill the bracket for usepackage automatically, I ran LatexTools: Build cache of LaTex packages manually but got

Then I investigated into the file latex_installed_packages.py. After I changed this line

and ran LatexTools: Build cache of LaTex packages, the autofill for usepackage worked successfully:

So could we change the method to

in latex_installed_packages.py?

If you don't mind, could I commit to Latextools to fix this issue?

[ig0774]

The default should probably be [] rather than ''. Other than that, feel free to create a PR.