Fix promise then chaining and disallow using try/catch in 5.1 in async and generator functions#1150
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Fix promise then chaining and disallow using try/catch in 5.1 in async and generator functions#1150
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# Conflicts: # src/transformation/visitors/errors.ts # src/transformation/visitors/return.ts # test/unit/builtins/async-await.spec.ts
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Fixed a problem in Promise.prototype.then lualib implementation where chained promises on already rejected/succeeded promises were not correctly fulfilled/rejected.
Async and generators are implemented using Lua coroutines, which do not play well in combination with pcall which we use to implement try catch. Implementing this becomes incredibly difficult as the proposed solution is to implement pcall as starting a coroutine and then using yield to throw an error. The problem is this interferes with both async and generators, and would require us to increase complexity of our try/catch even more. Therefore I left it out of scope for now, but at least we want to warn in this case.
Closes #1105