Fix sequence=0 becomes 0xffffffff when signing

[kallerosenbaum]

Also fixed two other non-broken but ugly instances of "if (number | undefined)"

[kallerosenbaum]

Fixes https://ledgerhq.atlassian.net/jira/software/c/projects/LL/issues/LL-8092

[codecov]

Codecov Report

Merging #698 (9ec9e1a) into master (c090d9e) will increase coverage by 0.04%.
The diff coverage is 81.81%.

❗ Current head 9ec9e1a differs from pull request most recent head ae05f1e. Consider uploading reports for the commit ae05f1e to get more accurate results

@@            Coverage Diff             @@
##           master     #698      +/-   ##
==========================================
+ Coverage   45.07%   45.12%   +0.04%     
==========================================
  Files          80       80              
  Lines        4867     4867              
  Branches      785      785              
==========================================
+ Hits         2194     2196       +2     
+ Misses       2659     2657       -2     
  Partials       14       14              

Impacted Files	Coverage Δ
packages/hw-app-eth/src/Eth.ts	85.15% <77.77%> (ø)
packages/cryptoassets/src/tokens.ts	74.25% <100.00%> (ø)
packages/hw-app-btc/src/BtcNew.ts	92.20% <100.00%> (ø)
packages/hw-app-eth/src/contracts.ts	72.00% <100.00%> (ø)
packages/hw-app-btc/src/splitTransaction.ts	74.19% <0.00%> (+2.15%)	⬆️

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[kallerosenbaum]

Fixes https://ledgerhq.atlassian.net/browse/LL-7946

[hzheng-ledger]

looks good to me. Thanks