Add null check to prevent potential runtime errors

[sigmoidr]

helpers.ts:

- return !!provider.providers?.some(provider => checkProviderIdentity({ provider, device })); + return Array.isArray(provider.providers) && !!provider.providers.some(provider => checkProviderIdentity({ provider, device }));

wallets.ts:

- checkProviderIdentity: ({ provider }) => !!provider && !!provider['ethereum'][ProviderIdentityFlag.Bitget], + checkProviderIdentity: ({ provider }) => !!provider && !!provider['ethereum'] && !!provider['ethereum'][ProviderIdentityFlag.Bitget]

[Adamj1232]

This null check looks good and passes testing