telemetry: include chained error message in reasonDesc (#5373)

* telemetry: include chained error message in reasonDesc

Problem:

When we use the function getTelemetryReasonDesc() we would lose information
about the underlying error in the case the error was a ToolkitError
with an underlying chained error. Only the message of the ToolkitError
was used.

So in telemetry we would be missing some information about the real cause
of the error.

Solution:

getTelemetryReasonDesc() will return a  message which consists
of all messages in the chain. It recursively calls in to the next
chained error of a ToolkitError and appends it to the final output.

This will give us some context about the higher level call as well
as the root of the issue.

The final message could look something like:
"Message A::Message B::Message C"

Signed-off-by: Nikolas Komonen <[email protected]>

* fix PR comments

Signed-off-by: Nikolas Komonen <[email protected]>

---------

Signed-off-by: Nikolas Komonen <[email protected]>

Author: nkomonen-amazon

packages/core/src/shared/errors.ts

@@ -243,11 +243,23 @@ export class ToolkitError extends Error implements ErrorInformation {
     }
 }
 
-export function getErrorMsg(err: Error | undefined): string | undefined {
+/**
+ * Derives an error message from the given error object.
+ * Depending on the Error, the property used to derive the message can vary.
+ *
+ * @param withCause Append the message(s) from the cause chain, recursively.
+ *                  The message(s) are delimited by ' | '. Eg: msg1 | causeMsg1 | causeMsg2
+ */
+export function getErrorMsg(err: Error | undefined, withCause = false): string | undefined {
     if (err === undefined) {
         return undefined
     }
 
+    const cause = (err as any).cause
+    if (withCause && cause) {
+        return `${err.message}${cause ? ' | ' + getErrorMsg(cause, true) : ''}`
+    }
+
     // Non-standard SDK fields added by the OIDC service, to conform to the OAuth spec
     // (https://datatracker.ietf.org/doc/html/rfc6749#section-4.1.2.1) :
     // - error: code per the OAuth spec
@@ -404,7 +416,7 @@ export function scrubNames(s: string, username?: string) {
  * @param err Error object, or message text
  */
 export function getTelemetryReasonDesc(err: unknown | undefined): string | undefined {
-    const m = typeof err === 'string' ? err : getErrorMsg(err as Error) ?? ''
+    const m = typeof err === 'string' ? err : getErrorMsg(err as Error, true) ?? ''
     const msg = scrubNames(m, _username)
 
     // Truncate to 200 chars.

packages/core/src/test/shared/errors.test.ts

@@ -10,6 +10,7 @@ import {
     formatError,
     getErrorMsg,
     getTelemetryReason,
+    getTelemetryReasonDesc,
     getTelemetryResult,
     isNetworkError,
     resolveErrorMessageToDisplay,
@@ -451,14 +452,33 @@ describe('util', function () {
             'unauthorized message'
         )
         assert.deepStrictEqual(getErrorMsg(undefined), undefined)
-        const err = new TestAwsError('ValidationException', 'aws validation msg 1', new Date())
-        assert.deepStrictEqual(getErrorMsg(err), 'aws validation msg 1')
-        ;(err as any).error_description = ''
-        assert.deepStrictEqual(getErrorMsg(err), 'aws validation msg 1')
-        ;(err as any).error_description = {}
-        assert.deepStrictEqual(getErrorMsg(err), 'aws validation msg 1')
-        ;(err as any).error_description = 'aws error desc 1'
-        assert.deepStrictEqual(getErrorMsg(err), 'aws error desc 1')
+        let awsErr = new TestAwsError('ValidationException', 'aws validation msg 1', new Date())
+        assert.deepStrictEqual(getErrorMsg(awsErr), 'aws validation msg 1')
+        ;(awsErr as any).error_description = ''
+        assert.deepStrictEqual(getErrorMsg(awsErr), 'aws validation msg 1')
+        ;(awsErr as any).error_description = {}
+        assert.deepStrictEqual(getErrorMsg(awsErr), 'aws validation msg 1')
+        ;(awsErr as any).error_description = 'aws error desc 1'
+        assert.deepStrictEqual(getErrorMsg(awsErr), 'aws error desc 1')
+
+        // Arg withCause=true
+        awsErr = new TestAwsError('ValidationException', 'aws validation msg 1', new Date())
+        let toolkitError = new ToolkitError('ToolkitError Message')
+        assert.deepStrictEqual(getErrorMsg(toolkitError, true), 'ToolkitError Message')
+
+        toolkitError = new ToolkitError('ToolkitError Message', { cause: awsErr })
+        assert.deepStrictEqual(getErrorMsg(toolkitError, true), `ToolkitError Message | aws validation msg 1`)
+
+        const nestedNestedToolkitError = new ToolkitError('C')
+        const nestedToolkitError = new ToolkitError('B', { cause: nestedNestedToolkitError })
+        toolkitError = new ToolkitError('A', { cause: nestedToolkitError })
+        assert.deepStrictEqual(getErrorMsg(toolkitError, true), `A | B | C`)
+    })
+
+    it('getTelemetryReasonDesc()', () => {
+        const err = new Error('Cause Message a/b/c/d.txt')
+        const toolkitError = new ToolkitError('ToolkitError Message', { cause: err })
+        assert.deepStrictEqual(getTelemetryReasonDesc(toolkitError), 'ToolkitError Message | Cause Message x/x/x/x.txt')
     })
 
     it('isNetworkError()', function () {