Still assign error's raw stack when prepareStackTrace is overridden

Signed-off-by: Nathan Sobo <nathan@github.com>

spec/compile-cache-spec.coffee

@@ -71,13 +71,16 @@ describe 'CompileCache', ->
         expect(CSONParser.parse.callCount).toBe 1
 
   describe 'overriding Error.prepareStackTrace', ->
-    it 'removes the override on the next tick', ->
+    it 'removes the override on the next tick, and always assigns the raw stack', ->
       Error.prepareStackTrace = -> 'a-stack-trace'
 
       error = new Error("Oops")
       expect(error.stack).toBe 'a-stack-trace'
+      expect(Array.isArray(error.getRawStack())).toBe true
 
       waits(1)
       runs ->
         error = new Error("Oops again")
-        expect(error.stack).not.toBe 'a-stack-trace'
+        console.log error.stack
+        expect(error.stack).toContain('compile-cache-spec.coffee')
+        expect(Array.isArray(error.getRawStack())).toBe true

src/compile-cache.js

@@ -158,29 +158,31 @@ require('source-map-support').install({
   }
 })
 
-var sourceMapPrepareStackTrace = Error.prepareStackTrace
+var prepareStackTraceWithSourceMapping = Error.prepareStackTrace
 
-// Enable Grim to access the raw stack by customizing Error.prepareStackTrace
-function prepareStackTraceWithRawStack (error, frames) {
+let prepareStackTrace = prepareStackTraceWithSourceMapping
+
+function prepareStackTraceWithRawStackAssignment (error, frames) {
   error.rawStack = frames
-  return sourceMapPrepareStackTrace(error, frames)
+  return prepareStackTrace(error, frames)
 }
 
-let prepareStackTrace = prepareStackTraceWithRawStack
-
-// Prevent coffee-script from reassigning Error.prepareStackTrace
 Object.defineProperty(Error, 'prepareStackTrace', {
-  get: function () { return prepareStackTrace },
+  get: function () {
+    return prepareStackTraceWithRawStackAssignment
+  },
+
   set: function (newValue) {
     prepareStackTrace = newValue
     process.nextTick(function () {
-      prepareStackTrace = prepareStackTraceWithRawStack
+      prepareStackTrace = prepareStackTraceWithSourceMapping
     })
   }
 })
 
 Error.prototype.getRawStack = function () { // eslint-disable-line no-extend-native
-  // Call this.stack first to ensure rawStack is generated
+  // Access this.stack to ensure prepareStackTrace has been run on this error
+  // because it assigns this.rawStack as a side-effect
   this.stack
   return this.rawStack
 }