Ensure JsonSourceFile has all the non-optional properties of SourceFile

[ghost]

Fixes microsoft/vscode#55665

[sheetalkamat]

Why is this done here. You dont want to set these for tsconfig files but set them only for modules which is done is parseSourceFile

[ghost]

In types.ts we declare interface JsonSourceFile extends SourceFile. So we will sometimes have a SourceFile object that actually comes from a .json file. When we try accessing properties that are non-optional on SourceFile, we'll crash if the json file didn't define them. (Like at for (const ref of sourceFile.referencedFiles) in getEditsForFileRename.ts which is the source of microsoft/vscode#55665)

The other option would be to make the properties added by noPragmas optional and handle them at the use-site, if you'd prefer that.

[sheetalkamat]

I think you want to set them you want to do that in parseSourceFile https://github.com/Microsoft/TypeScript/blob/master/src/compiler/parser.ts#L693

[ghost]

parseSourceFile won't be called for a json source file though. (See the branch in createSourceFile that calls parseJsonText instead of parseSourceFile.) But we could move the code to createSourceFile which they both call, would that be better?

[ghost]

@sheetalkamat Thoughts?

[sheetalkamat]

I think you want to change

        if (languageVersion === ScriptTarget.JSON) {
            result = Parser.parseJsonText(fileName, sourceText, languageVersion, /*syntaxCursor*/ undefined, setParentNodes);
        }
        else {
            result = Parser.parseSourceFile(fileName, sourceText, languageVersion, /*syntaxCursor*/ undefined, setParentNodes, scriptKind);
        }

to

if (languageVersion === ScriptTarget.JSON) {
            result = Parser.parseSourceFile(fileName, sourceText, languageVersion, /*syntaxCursor*/ undefined, setParentNodes, ScriptKind.Json);
        }
        else {
            result = Parser.parseSourceFile(fileName, sourceText, languageVersion, /*syntaxCursor*/ undefined, setParentNodes, scriptKind);
        }