fix nil dereference

[synzhu]

No description provided.

[peterargue]

looks good

[codecov-commenter]

Codecov Report

Merging #1330 (8dc5771) into master (449a3b5) will decrease coverage by 0.00%.
The diff coverage is 44.11%.

@@            Coverage Diff             @@
##           master    #1330      +/-   ##
==========================================
- Coverage   56.22%   56.21%   -0.01%     
==========================================
  Files         501      500       -1     
  Lines       31095    31072      -23     
==========================================
- Hits        17483    17468      -15     
+ Misses      11243    11236       -7     
+ Partials     2369     2368       -1     

Flag	Coverage Δ
unittests	56.21% <44.11%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
engine/consensus/matching/core.go	50.00% <ø> (ø)
fvm/blocks.go	58.82% <ø> (ø)
fvm/errors/accounts.go	0.00% <0.00%> (ø)
fvm/errors/base.go	0.00% <0.00%> (ø)
fvm/errors/codes.go	100.00% <ø> (ø)
fvm/errors/execution.go	4.16% <0.00%> (ø)
fvm/handler/accountKey.go	1.30% <ø> (ø)
fvm/handler/metrics.go	65.21% <ø> (ø)
fvm/transactionInvocator.go	73.61% <ø> (ø)
fvm/transactionSequenceNum.go	62.50% <ø> (ø)
... and 12 more

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[huitseeker]

Hmm, not what I expected, but good fix!