fix(bug): Fixes panic in `new_regtest()` #1909

Job	Run time
Versioning	0s
Get disk name / Get Mainnet cached disk	35s
Build CD Docker / Build images	1m 43s
Test CD default Docker config file / Test default-conf in Docker	1m 38s
Test CD testnet Docker config file / Test testnet-conf in Docker	1m 34s
Test CD custom Docker config file / Test custom-conf in Docker	20s
Deploy single ${{ inputs.network }} instance	0s
Deploy ${{ matrix.network }} nodes	0s
Open or update issues for release failures	0s
	5m 50s

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