Convert @bugsnag/core/lib/node-fallback-stack to TypeScript

packages/core/package.json

@@ -17,7 +17,6 @@
     "./lib/derecursify": "./src/lib/derecursify.js",
     "./lib/metadata-delegate": "./src/lib/metadata-delegate.js",
     "./lib/callback-runner": "./src/lib/callback-runner.js",
-    "./lib/node-fallback-stack": "./src/lib/node-fallback-stack.js",
     "./lib/path-normalizer": "./src/lib/path-normalizer.js",
     "./lib/validators/string-with-length": "./src/lib/validators/string-with-length.js",
     "./lib/validators/list-of-functions": "./src/lib/validators/list-of-functions.js",

packages/core/src/index.ts

@@ -7,6 +7,7 @@ export { default as cloneClient } from './lib/clone-client'
 export { default as jsonPayload } from './lib/json-payload'
 export { default as intRange } from './lib/validators/int-range'
 export { default as isError } from './lib/iserror'
+export { default as nodeFallbackStack } from './lib/node-fallback-stack'
 export { default as runSyncCallbacks } from './lib/sync-callback-runner'
 
 export * from './common'

packages/core/src/lib/node-fallback-stack.ts

@@ -0,0 +1,37 @@
+// The utilities in this file are used to save the stackframes from a known execution context
+// to use when a subsequent error has no stack frames. This happens with a lot of
+// node's builtin async callbacks when they return from the native layer with no context
+// for example:
+//
+//   fs.readFile('does not exist', (err) => {
+//     /* node 8 */
+//     err.stack = "ENOENT: no such file or directory, open 'nope'"
+//     /* node 4,6 */
+//     err.stack = "Error: ENOENT: no such file or directory, open 'nope'\n    at Error (native)"
+//   })
+
+interface NodeFallbackStack {
+  getStack: () => string | undefined
+  maybeUseFallbackStack: (err: Error, fallbackStack: string) => Error
+}
+
+const nodeFallbackStack: NodeFallbackStack = {
+  // Gets the stack string for the current execution context
+  getStack: () => {
+    // slice(3) removes the first line + this function's frame + the caller's frame,
+    // so the stack begins with the caller of this function
+    return (new Error()).stack?.split('\n').slice(3).join('\n')
+  },
+
+  // Given an Error and a fallbackStack from getStack(), use the fallbackStack
+  // if error.stack has no genuine stackframes (according to the example above)
+  maybeUseFallbackStack: (err, fallbackStack) => {
+    const lines = err.stack?.split('\n')
+    if (lines?.length === 1 || (lines?.length === 2 && /at Error \(native\)/.test(lines[1]))) {
+      err.stack = `${lines[0]}\n${fallbackStack}`
+    }
+    return err
+  }
+}
+
+export default nodeFallbackStack

packages/plugin-contextualize/contextualize.js

@@ -1,12 +1,11 @@
-const { getStack } = require('@bugsnag/core/lib/node-fallback-stack')
-const { cloneClient } = require('@bugsnag/core')
+const { cloneClient, nodeFallbackStack } = require('@bugsnag/core')
 
 module.exports = {
   name: 'contextualize',
   load: client => {
     const contextualize = (fn, onError) => {
       // capture a stacktrace in case a resulting error has nothing
-      const fallbackStack = getStack()
+      const fallbackStack = nodeFallbackStack.getStack()
 
       const clonedClient = cloneClient(client)
 

packages/plugin-intercept/intercept.js

@@ -1,4 +1,4 @@
-const { getStack, maybeUseFallbackStack } = require('@bugsnag/core/lib/node-fallback-stack')
+const { nodeFallbackStack } = require('@bugsnag/core')
 
 module.exports = {
   name: 'intercept',
@@ -10,12 +10,12 @@ module.exports = {
       }
 
       // capture a stacktrace in case a resulting error has nothing
-      const fallbackStack = getStack()
+      const fallbackStack = nodeFallbackStack.getStack()
 
       return (err, ...data) => {
         if (err) {
           // check if the stacktrace has no context, if so, if so append the frames we created earlier
-          if (err.stack) maybeUseFallbackStack(err, fallbackStack)
+          if (err.stack) nodeFallbackStack.maybeUseFallbackStack(err, fallbackStack)
           const event = client.Event.create(err, true, {
             severity: 'warning',
             unhandled: false,

packages/plugin-node-uncaught-exception/uncaught-exception.js

@@ -1,4 +1,4 @@
-const { maybeUseFallbackStack } = require('@bugsnag/core/lib/node-fallback-stack')
+const { nodeFallbackStack } = require('@bugsnag/core')
 
 let _handler
 module.exports = {
@@ -12,7 +12,7 @@ module.exports = {
 
       // check if the stacktrace has no context, if so append the frames we created earlier
       // see plugin-contextualize for where this is created
-      if (err.stack && c.fallbackStack) maybeUseFallbackStack(err, c.fallbackStack)
+      if (err.stack && c.fallbackStack) nodeFallbackStack.maybeUseFallbackStack(err, c.fallbackStack)
 
       const event = c.Event.create(err, false, {
         severity: 'error',