Add Result type guards (#8835)

### Description

Adds type guards for the Result type

packages/sdk/base/src/result.test.ts

@@ -0,0 +1,20 @@
+import { Err, isOk, Ok, Result } from '.'
+
+// These tests are just to check the typescript compiler
+describe('discriminated collection functions', () => {
+  const trueValue = Ok(true)
+  const falseValue = Err(new Error())
+  const collection: Array<Result<boolean, Error>> = [trueValue, falseValue]
+
+  it('can filter to the true value', () => {
+    const ok = collection.filter(isOk)
+    expect(ok.map((_) => _.result)).toEqual([true])
+  })
+
+  it('can find in collection', () => {
+    const ok = collection.find(isOk)
+    if (ok) {
+      expect(ok.result).toEqual(true)
+    }
+  })
+})

packages/sdk/base/src/result.ts

@@ -88,3 +88,15 @@ export function parseJsonAsResult(data: string) {
     return Err(new JSONParseError(error))
   }
 }
+
+export function isOk<TResult, TError extends Error>(
+  result: Result<TResult, TError>
+): result is OkResult<TResult> {
+  return result.ok
+}
+
+export function isErr<TResult, TError extends Error>(
+  result: Result<TResult, TError>
+): result is ErrorResult<TError> {
+  return !result.ok
+}