feat(types): update to Typescript 3.9 (#1106)

packages/runtime-core/src/componentOptions.ts

@@ -135,7 +135,7 @@ export interface ComponentOptionsBase<
 
   // type-only differentiator to separate OptionWithoutProps from a constructor
   // type returned by defineComponent() or FunctionalComponent
-  call?: never
+  call?: (this: unknown, ...args: unknown[]) => never
   // type-only differentiators for built-in Vnode types
   __isFragment?: never
   __isTeleport?: never
@@ -197,9 +197,9 @@ export interface MethodOptions {
 }
 
 export type ExtractComputedReturns<T extends any> = {
-  [key in keyof T]: T[key] extends { get: Function }
-    ? ReturnType<T[key]['get']>
-    : ReturnType<T[key]>
+  [key in keyof T]: T[key] extends { get: (...args: any[]) => infer TReturn }
+    ? TReturn
+    : T[key] extends (...args: any[]) => infer TReturn ? TReturn : never
 }
 
 type WatchOptionItem =

packages/runtime-core/src/components/Suspense.ts

@@ -244,6 +244,7 @@ function createSuspenseBoundary(
   /* istanbul ignore if */
   if (__DEV__ && !__TEST__ && !hasWarned) {
     hasWarned = true
+    // @ts-ignore `console.info` cannot be null error
     console[console.info ? 'info' : 'log'](
       `<Suspense> is an experimental feature and its API will likely change.`
     )