duplicate_key: Handle raw_params being None sometimes

[PiDelport]

This is a small bug-fix update to #995 that I missed in my local testing. (Whoops.)

[PiDelport]

@camilonova: I hope you don't mind a quick review. :)

[codecov]

Codecov Report

Merging #1084 into master will increase coverage by 0.08%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1084      +/-   ##
==========================================
+ Coverage    84.3%   84.38%   +0.08%     
==========================================
  Files          24       24              
  Lines        1325     1326       +1     
  Branches      181      181              
==========================================
+ Hits         1117     1119       +2     
  Misses        157      157              
+ Partials       51       50       -1

Impacted Files	Coverage Δ
debug_toolbar/panels/sql/panel.py	66.66% <100%> (+0.2%)	⬆️
debug_toolbar/panels/headers.py	100% <0%> (+4.54%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 844353e...b6c46dd. Read the comment docs.

[matthiask]

Thank you!