Fix crash in EthereumAbi encoder with wrong parameter type

[optout21]

Description

Fix crash in EthereumAbi encoder with wrong parameter type. Fixes #895 .

Testing instructions

Unit tests, incl. new test.

Types of changes

Checklist

• Prefix PR title with [WIP] if necessary.
• Add tests to cover changes as needed.
• Update documentation as needed.
• If there is a related Issue, mention it in the description (e.g. 'Fixes Adopt Zilliqa to bech32 address format #444 ).

[optout21]

Wrong branch, correct PR is #897 .

[codecov]

Codecov Report

Merging #896 into master will increase coverage by <.01%.
The diff coverage is 88.23%.

@@            Coverage Diff             @@
##           master     #896      +/-   ##
==========================================
+ Coverage   92.41%   92.42%   +<.01%     
==========================================
  Files         417      417              
  Lines       12040    12078      +38     
==========================================
+ Hits        11127    11163      +36     
- Misses        913      915       +2

Impacted Files	Coverage Δ
src/Coin.cpp	100% <ø> (ø)	⬆️
src/interface/TWEthereumAbiFunction.cpp	94.75% <88.23%> (-0.33%)	⬇️
src/Harmony/Staking.h	98.33% <0%> (+0.08%)	⬆️
src/Harmony/Signer.cpp	97.28% <0%> (+0.11%)	⬆️

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