Avoid crushing when can't trsh scan

[alongd]

In trsh scan_quality_check(), ARC checks broken bond and any lowest conformation, excluding those with broken bonds. Ths is step 1.2 in the function.
Here we make a minor fix to a KeyError in the line actions = {'change conformer': conf_xyzs[min_index]}, and now we only call conf_xyzs[min_index] if the length of the list and the index value makes sense.

[codecov]

Codecov Report

Attention: Patch coverage is 83.33333% with 1 line in your changes missing coverage. Please review.

Project coverage is 73.96%. Comparing base (8665b73) to head (82f6c48).
Report is 3 commits behind head on main.

Files	Patch %	Lines
arc/job/trsh.py	83.33%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #763      +/-   ##
==========================================
- Coverage   73.96%   73.96%   -0.01%     
==========================================
  Files         101      101              
  Lines       27776    27777       +1     
  Branches     5816     5817       +1     
==========================================
  Hits        20544    20544              
  Misses       5773     5773              
- Partials     1459     1460       +1     

Flag	Coverage Δ
unittests	73.96% <83.33%> (-0.01%)	⬇️

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[NellyMitnik]

I ran a species that caused ARC to crush for the corresponding error. With this fix, it converged successfully.

    multiplicity 2
    1  O u0 p2 c0 {5,S} {12,S}
    2  O u1 p2 c0 {6,S}
    3  C u0 p0 c0 {4,S} {6,D} {8,S}
    4  C u0 p0 c0 {3,S} {7,D} {9,S}
    5  C u0 p0 c0 {1,S} {7,D} {10,S}
    6  C u0 p0 c0 {2,S} {3,D} {11,S}
    7  C u0 p0 c0 {4,D} {5,D}
    8  H u0 p0 c0 {3,S}
    9  H u0 p0 c0 {4,S}
    10 H u0 p0 c0 {5,S}
    11 H u0 p0 c0 {6,S}
    12 H u0 p0 c0 {1,S}
  label: C5H5O2(505)