Apply SourceMaps type to redux actions

[ryanjduffy]

Fixes #7925

Summary of Changes

• Change instances of source maps to use typeof SourceMaps instead of any/Object
• Add a couple more types to address flow inference issue (see below)

Considerations

I couldn't find a way to import the typeof the default export of a module alongside named imports from the same module.

import typeof SourceMaps, { isGeneratedId } from "devtools-source-map";

Originally, I included two imports and suppressed the eslint error but changed when I realized the frequency this would be required. The current approach is to import the default export and use typeof in the instance typing later.

import typeof SourceMaps, { isGeneratedId } from "devtools-source-map";
// later
const sourceMaps: typeof SourceMaps = ...;

I also ran into a couple issues that seem to trace back to flow. I've documented them inline but noting them here for traceability in GitHub.

Explicitly typing an array wrapped by a Promise
facebook/flow#5294

Unable to correctly type the result of a spread on a union type.
facebook/flow#7298

[darkwing]

Thank you for kick-starting this! Do you plan on continuing this PR?

[ryanjduffy]

I do! Thanks for the reminder, @darkwing!

[ryanjduffy]

Not sure if this is the right approach. From what I read in XScope.search(), displayName will always be present and location may be present but thread shouldn't be. However, it was accessed below so perhaps I've misread.

[ryanjduffy]

Not sure why source was passed here but seems invalid given the signature of getOriginalLocation.

[jasonLaster]

looks like a good catch

[ryanjduffy]

@jasonLaster + @darkwing - I think this is ready for review. Lemme know what you think.

[jasonLaster]

quick scan. this looks really good.