Maximum call stack size exceeded when loading solc-json compilers <0.6.2 in VerificationService.init()

[kuzdogan]

Discovered on #1465 in the test The downloadFunction for the solc-js compilers getSolcJs fails at the import stage for compilers earlier than 0.6.2. Weirdly this does not happen when the server is started and the compiler is downloaded and loaded for a contract but only on the init stage.

To reproduce:

• Make sure to run on a non-native platform (ie. no linux-amd64, macos-amd64, windows-amd/64) or override the platform
• Check out c710f93b4e452e88086db2b41f58f0d382431ffe
• Run the test with cd services/server && npx mocha test/unit/VerificationService.spec.ts

The test will fail with Maximum call stack size exceeded.

• Now remove version 0.1.1 on line 36 and the tests should pass.

To compare initializing to downloading on the fly when the server runs:

• Instead of 0.1.1 in the mock object add: "0.4.18": "soljson-v0.4.18+commit.9cf6e910.js",
• Run the tests and it will fail.
• Delete the downloaded 0.4.18 compiler and run the server.
• Verify a contract with 0.4.18 e.g. the USDT contract on Eth Mainnet (1) with Etherscan: 0xdac17f958d2ee523a2206206994597c13d831ec7
• This time the compiler will download, load successfully and compile the contract.