Fix wrong exception arg and fix some types

[meliache]

I changed my linter to one that also checks types (i.e. the pyright) language server and found some issues in the gbasf2 batch code, which are fixed with this.

• get_unique_lfns could return either list or set. Make it return only list and fix type annotation
• only replace the gbasf2 env HOME with local HOME if local HOME is set
• add type annotations to query_lpns
• fix wrong stderr argument to error raised in setup_dirac_proxy

[codecov-commenter]

Codecov Report

Merging #149 (0ad0c1c) into main (a81a814) will decrease coverage by 0.26%. The diff coverage is 16.66%.

@@            Coverage Diff             @@
##             main     #149      +/-   ##
==========================================
- Coverage   57.38%   57.12%   -0.27%     
==========================================
  Files          23       23              
  Lines        1516     1523       +7     
==========================================
  Hits          870      870              
- Misses        646      653       +7     

Impacted Files	Coverage Δ
b2luigi/batch/processes/gbasf2.py	41.17% <16.66%> (-0.69%)	:arrow_down:

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