Duplicate errors in error list after build

[mhegazy]

Issue Type: Bug

1. Create file a.js:

// @ts-check

/** @type {number} */
var a = "";

2. Create file tsconfig.json

{
    "compilerOptions": {
        "allowJs": true,
        "pretty": false,
        "noEmit": true
    }
}

3. Open code
4. Run build command

Observe error list is updated with errors:

5. Double click on the error message, a.js is now open

Observe error list now has duplicate errors:

Note: this does not seem to happen for a .ts file

VS Code version: Code 1.22.2 (3aeede7, 2018-04-12T16:38:45.278Z)
OS version: Windows_NT x64 10.0.16299

System Info

Item	Value
CPUs	Intel(R) Core(TM) i7-8650U CPU @ 1.90GHz (8 x 2112)
Memory (System)	15.93GB (6.67GB free)
Process Argv	C:\Program Files\Microsoft VS Code\Code.exe stc
Screen Reader	no
VM	0%

Extensions (1)

Extension	Author (truncated)	Version
xml	Dot	1.9.2

[mjbvz]

Root cause is that the build error comes from 'typescript' while the in-editor error comes from 'javascript' (indicated by the [ts] and [js]). Potential fixes:

• Only use a single error provider for both JS and TS. This probably makes the most sense since you can have mixed projects. Not sure why these were split originally
• Make problem view smarter so it can de-dup these two languages
• Make errors detected in js files by build task get reported as [js]

[mhegazy]

Thanks @mjbvz. Do you expect this to be in insiders tomorrow?

[mjbvz]

Yes this will be in the next insiders build