feat: add stack to stacktraceless "exceptions" (#1472)

cypress/e2e/error-tracking.cy.ts

@@ -41,6 +41,22 @@ describe('Exception capture', () => {
             cy.wait('@exception-autocapture-script')
         })
 
+        it('adds stacktrace to captured strings', () => {
+            cy.get('[data-cy-exception-string-button]').click()
+
+            // ugh
+            cy.wait(1500)
+
+            cy.phCaptures({ full: true }).then((captures) => {
+                expect(captures.map((c) => c.event)).to.deep.equal(['$pageview', '$autocapture', '$exception'])
+                expect(captures[2].event).to.be.eql('$exception')
+                expect(captures[2].properties.$exception_list[0].stacktrace.frames.length).to.be.eq(1)
+                expect(captures[2].properties.$exception_list[0].stacktrace.frames[0].function).to.be.eq(
+                    'HTMLButtonElement.onclick'
+                )
+            })
+        })
+
         it('autocaptures exceptions', () => {
             cy.get('[data-cy-button-throws-error]').click()
 

playground/cypress-full/index.html

@@ -40,6 +40,10 @@
         Send an exception
     </button>
 
+    <button data-cy-exception-string-button onclick="posthog.captureException('I am a plain old string', { extra_prop: 2 })">
+        Capture as string
+    </button>
+
     <br />
 
     <script>

playground/cypress/index.html

@@ -52,6 +52,10 @@
         Capture an exception
     </button>
 
+    <button data-cy-exception-string-button onclick="posthog.captureException('I am a plain old string', { extra_prop: 2 })">
+        Capture as string
+    </button>
+
     <script>
         !function(t,e){var o,n,p,r;e.__SV||(window.posthog=e,e._i=[],e.init=function(i,s,a){function g(t,e){var o=e.split(".");2==o.length&&(t=t[o[0]],e=o[1]),t[e]=function(){t.push([e].concat(Array.prototype.slice.call(arguments,0)))}}(p=t.createElement("script")).type="text/javascript",p.async=!0,p.src=s.api_host+"/static/array.js",(r=t.getElementsByTagName("script")[0]).parentNode.insertBefore(p,r);var u=e;for(void 0!==a?u=e[a]=[]:a="posthog",u.people=u.people||[],u.toString=function(t){var e="posthog";return"posthog"!==a&&(e+="."+a),t||(e+=" (stub)"),e},u.people.toString=function(){return u.toString(1)+".people (stub)"},o="capture identify alias people.set people.set_once set_config register register_once unregister opt_out_capturing has_opted_out_capturing opt_in_capturing reset isFeatureEnabled onFeatureFlags getSurveys getActiveMatchingSurveys captureException".split(" "),n=0;n<o.length;n++)g(u,o[n]);e._i.push([i,s,a])},e.__SV=1)}(document,window.posthog||[]);
     </script>

src/extensions/exception-autocapture/error-conversion.ts

@@ -56,7 +56,7 @@ export interface ErrorConversions {
 const ERROR_TYPES_PATTERN =
     /^(?:[Uu]ncaught (?:exception: )?)?(?:((?:Eval|Internal|Range|Reference|Syntax|Type|URI|)Error): )?(.*)$/i
 
-export function parseStackFrames(ex: Error & { framesToPop?: number; stacktrace?: string }): StackFrame[] {
+export function parseStackFrames(ex: Error & { stacktrace?: string }, framesToPop: number = 0): StackFrame[] {
     // Access and store the stacktrace property before doing ANYTHING
     // else to it because Opera is not very good at providing it
     // reliably in other circumstances.
@@ -65,7 +65,9 @@ export function parseStackFrames(ex: Error & { framesToPop?: number; stacktrace?
     const skipLines = getSkipFirstStackStringLines(ex)
 
     try {
-        return defaultStackParser(stacktrace, skipLines)
+        const frames = defaultStackParser(stacktrace, skipLines)
+        // frames are reversed so we remove the from the back of the array
+        return frames.slice(0, frames.length - framesToPop)
     } catch {
         // no-empty
     }
@@ -146,17 +148,26 @@ function errorPropertiesFromString(candidate: string, metadata?: ErrorMetadata):
         ? candidate
         : metadata?.defaultExceptionMessage
 
+    const exception: Exception = {
+        type: exceptionType,
+        value: exceptionMessage,
+        mechanism: {
+            handled,
+            synthetic,
+        },
+    }
+
+    if (metadata?.syntheticException) {
+        // Kludge: strip the last frame from a synthetically created error
+        // so that it does not appear in a users stack trace
+        const frames = parseStackFrames(metadata.syntheticException, 1)
+        if (frames.length) {
+            exception.stacktrace = { frames }
+        }
+    }
+
     return {
-        $exception_list: [
-            {
-                type: exceptionType,
-                value: exceptionMessage,
-                mechanism: {
-                    handled,
-                    synthetic,
-                },
-            },
-        ],
+        $exception_list: [exception],
         $exception_level: 'error',
     }
 }
@@ -206,17 +217,26 @@ function errorPropertiesFromObject(candidate: Record<string, unknown>, metadata?
         ? metadata.overrideExceptionMessage
         : `Non-Error ${'exception'} captured with keys: ${extractExceptionKeysForMessage(candidate)}`
 
+    const exception: Exception = {
+        type: exceptionType,
+        value: exceptionMessage,
+        mechanism: {
+            handled,
+            synthetic,
+        },
+    }
+
+    if (metadata?.syntheticException) {
+        // Kludge: strip the last frame from a synthetically created error
+        // so that it does not appear in a users stack trace
+        const frames = parseStackFrames(metadata?.syntheticException, 1)
+        if (frames.length) {
+            exception.stacktrace = { frames }
+        }
+    }
+
     return {
-        $exception_list: [
-            {
-                type: exceptionType,
-                value: exceptionMessage,
-                mechanism: {
-                    handled,
-                    synthetic,
-                },
-            },
-        ],
+        $exception_list: [exception],
         $exception_level: isSeverityLevel(candidate.level) ? candidate.level : 'error',
     }
 }
@@ -259,7 +279,7 @@ export function errorToProperties(
     } else if (isPlainObject(candidate) || isEvent(candidate)) {
         // group these by using the keys available on the object
         const objectException = candidate as Record<string, unknown>
-        return errorPropertiesFromObject(objectException)
+        return errorPropertiesFromObject(objectException, metadata)
     } else if (isUndefined(error) && isString(event)) {
         let name = 'Error'
         let message = event

src/extensions/exception-autocapture/stack-trace.ts

@@ -51,7 +51,6 @@ export interface StackFrame {
 }
 
 const WEBPACK_ERROR_REGEXP = /\(error: (.*)\)/
-const STRIP_FRAME_REGEXP = /captureException/
 const STACKTRACE_FRAME_LIMIT = 50
 
 const UNKNOWN_FUNCTION = '?'
@@ -210,14 +209,6 @@ export function reverseAndStripFrames(stack: ReadonlyArray<StackFrame>): StackFr
 
     localStack.reverse()
 
-    if (STRIP_FRAME_REGEXP.test(getLastStackFrame(localStack).function || '')) {
-        localStack.pop()
-
-        if (STRIP_FRAME_REGEXP.test(getLastStackFrame(localStack).function || '')) {
-            localStack.pop()
-        }
-    }
-
     return localStack.slice(0, STACKTRACE_FRAME_LIMIT).map((frame) => ({
         ...frame,
         filename: frame.filename || getLastStackFrame(localStack).filename,

src/extensions/exception-autocapture/type-checking.ts

@@ -27,6 +27,7 @@ export function isError(candidate: unknown): candidate is Error {
         case '[object Error]':
         case '[object Exception]':
         case '[object DOMException]':
+        case '[object DOMError]':
             return true
         default:
             return isInstanceOf(candidate, Error)

src/posthog-core.ts

@@ -1824,14 +1824,15 @@ export class PostHog {
 
     /** Capture a caught exception manually */
     captureException(error: Error, additionalProperties?: Properties): void {
+        const syntheticException = new Error('PostHog syntheticException')
         const properties: Properties = isFunction(assignableWindow.__PosthogExtensions__?.parseErrorAsProperties)
-            ? assignableWindow.__PosthogExtensions__.parseErrorAsProperties([
-                  error.message,
-                  undefined,
-                  undefined,
-                  undefined,
-                  error,
-              ])
+            ? assignableWindow.__PosthogExtensions__.parseErrorAsProperties(
+                  [error.message, undefined, undefined, undefined, error],
+                  // create synthetic error to get stack in cases where user input does not contain one
+                  // creating the exceptionas soon into our code as possible means we should only have to
+                  // remove a single frame (this 'captureException' method) from the resultant stack
+                  { syntheticException }
+              )
             : {
                   $exception_level: 'error',
                   $exception_list: [

src/types.ts

@@ -579,6 +579,7 @@ export type ErrorEventArgs = [
 export type ErrorMetadata = {
     handled?: boolean
     synthetic?: boolean
+    syntheticException?: Error
     overrideExceptionType?: string
     overrideExceptionMessage?: string
     defaultExceptionType?: string