fix EvaluationDetail.reason to be nullable so we can get rid of NonNullableLDEvaluationReason type (#49)

* remove deprecated options and function

* rm references to obsolete function

* restore deprecation logic, just leave the data empty

* remove samplingInterval from TS test code

* fix TS test code again

* fix EvaluationDetail.reason to be nullable so we can get rid of NonNullableLDEvaluationReason type

* fix TS test code

Author: eli-darkly

test-types.ts

@@ -76,7 +76,7 @@ var jsonFlagValue: ld.LDFlagValue = client.variation('key', [ 'a', 'b' ]);
 var detail: ld.LDEvaluationDetail = client.variationDetail('key', 'default');
 var detailValue: ld.LDFlagValue = detail.value;
 var detailIndex: number | undefined = detail.variationIndex;
-var detailReason: ld.LDEvaluationReason = detail.reason;
+var detailReason: ld.LDEvaluationReason | undefined = detail.reason;
 
 client.setStreaming(true);
 client.setStreaming();

typings.d.ts

@@ -351,12 +351,8 @@ declare module 'launchdarkly-js-sdk-common' {
   /**
    * Describes the reason that a flag evaluation produced a particular value. This is
    * part of the [[LDEvaluationDetail]] object returned by [[LDClient.variationDetail]].
-   *
-   * This type is separate from `[[LDEvaluationReason]]` for backwards compatibility. In
-   * earlier versions of this SDK, `[[LDEvaluationReason]]` was incorrectly defined as
-   * being non-nullable.
    */
-  interface NonNullableLDEvaluationReason {
+  interface LDEvaluationReason {
     /**
      * The general category of the reason:
      *
@@ -392,14 +388,6 @@ declare module 'launchdarkly-js-sdk-common' {
     prerequisiteKey?: string;
   }
 
-  /**
-   * Describes the reason that a flag evaluation produced a particular value. This is
-   * part of the [[LDEvaluationDetail]] object returned by [[LDClient.variationDetail]].
-   *
-   * Will be null when `[[LDOptions.evaluationReasons]]` is `false`.
-   */
-  export type LDEvaluationReason = NonNullableLDEvaluationReason | null;
-
   /**
    * An object that combines the result of a feature flag evaluation with information about
    * how it was calculated.
@@ -423,8 +411,10 @@ declare module 'launchdarkly-js-sdk-common' {
 
     /**
      * An object describing the main factor that influenced the flag evaluation value.
+     * This will be `null`/`undefined` if the SDK was not configured to get evaluation
+     * reasons.
      */
-    reason: LDEvaluationReason;
+    reason?: LDEvaluationReason;
   }
 
   /**