Update to TypeScript 3.7 (#3275)

and update to prettier 1.19

Also, update `assert()` and remove not null assertions where possibly
in `cli`.

Closes #3273

1 files changed, 7 insertions, 12 deletions

diff --git a/cli/js/util.ts b/cli/js/util.ts
index 77dc7db5b..54230af1f 100644
--- a/cli/js/util.ts
+++ b/cli/js/util.ts
@@ -26,7 +26,7 @@ export function log(...args: unknown[]): void {
 }
 
 // @internal
-export function assert(cond: boolean, msg = "assert"): void {
+export function assert(cond: unknown, msg = "assert"): asserts cond {
   if (!cond) {
     throw Error(msg);
   }
@@ -74,11 +74,9 @@ export type Resolvable<T> = Promise<T> & ResolvableMethods<T>;
 // @internal
 export function createResolvable<T>(): Resolvable<T> {
   let methods: ResolvableMethods<T>;
-  const promise = new Promise<T>(
-    (resolve, reject): void => {
-      methods = { resolve, reject };
-    }
-  );
+  const promise = new Promise<T>((resolve, reject): void => {
+    methods = { resolve, reject };
+  });
   // TypeScript doesn't know that the Promise callback occurs synchronously
   // therefore use of not null assertion (`!`)
   return Object.assign(promise, methods!) as Resolvable<T>;
@@ -97,12 +95,9 @@ export function unreachable(): never {
 // @internal
 export function hexdump(u8: Uint8Array): string {
   return Array.prototype.map
-    .call(
-      u8,
-      (x: number): string => {
-        return ("00" + x.toString(16)).slice(-2);
-      }
-    )
+    .call(u8, (x: number): string => {
+      return ("00" + x.toString(16)).slice(-2);
+    })
     .join(" ");
 }