added fullTypeCheckFlag to TypeChecker

[vladima]

LS now uses 2 instances of typechecker:

• typeInfoResolver - created via getTypeChecker(/*fullTypeCheck*/ false) - used by quickinfo\dot completion etc..
• fullTypeCheckChecker - created via getTypeChecker(/*fullTypeCheck*/ true) - used to get semantic diagnostics.

fullTypeCheck parameter in the getTypeChecker controls if typechecker can shortcut and answer more quickly (producing less error messages but they are still ignored when fullTypeCheck === true)

[CyrusNajmabadi]

should we instead just augment checkTypeAssignableTo to check the fullTypeCheck flag?

[mhegazy]

do not create it here. create it on demand. this will do a full bind, and unless the current operation is getSemanticDiagnositcs, this is wasted.

[mhegazy]

i do not really care for the name that much. and this is used in only one place, so the extra layer of abstraction, is not really useful, i would just put it in getSemanticDiagnostics, to recreate if it does not exist and forget about it.

[vladima]

My preference in avoiding errors is to leave only one way that will do things right. Since accessing variable directly might fail without prior check - then this only was should be "always use function, do not touch the variable"

[mhegazy]

👍