201729 2019-09-12 11:22:54 -0700 Uncaught Exception: null is not an object (evaluating 'Object.keys(propertyNames)​')​ (at JavaScriptRuntimeCompletionProvider.js:​244:​57)​ 2019-09-13 11:59:19 -0700 1 1 1 Unclassified WebKit Web Inspector WebKit Nightly Build All All RESOLVED FIXED InRadar P2 Normal --- 1 joepeck joepeck hi inspector-bugzilla-changes joepeck webkit-bug-importer oldest_to_newest 1570309 0 joepeck 2019-09-12 11:22:54 -0700 Not sure exactly how to reproduce yet. Was typing: 1. js> entry.contentView.| When Uncaught Exception: ---------------------- null is not an object (evaluating 'Object.keys(propertyNames)​')​ (at JavaScriptRuntimeCompletionProvider.js:​244:​57)​ keys @ [native code]​ receivedObjectPropertyNames @ JavaScriptRuntimeCompletionProvider.js:​244:​57 receivedObjectPropertyNames @ [native code]​ mycallback @ RemoteObject.js:​516:​21 _dispatchResponseToCallback @ Connection.js:​148:​27 _dispatchResponse @ Connection.js:​118:​45 dispatch @ Connection.js:​70:​35 dispatchMessageFromTarget @ TargetManager.js:​143:​35 dispatchMessageFromTarget @ TargetObserver.js:​42:​51 dispatchEvent @ InspectorBackend.js:​340:​42 _dispatchEvent @ Connection.js:​195:​32 dispatch @ Connection.js:​72:​32 dispatch @ InspectorBackend.js:​178:​52 ?​ @ MessageDispatcher.js:​42:​34 ---------------------- 1570315 1 joepeck 2019-09-12 11:46:40 -0700 This seems like a race when typing very fast. Calls to: RuntimeAgent.releaseObjectGroup("completion") From a prior evaluation will wipe out an ongoing request. --- Typing: `entry.contentView` quickly in the quick console when paused: [Log] request: { "id": 675, "method": "Debugger.evaluateOnCallFrame", "params": { "callFrameId": "{\"ordinal\":2,\"injectedScriptId\":1}", "expression": "\n//# sourceURL=__WebInspectorInternal__\nentry", "objectGroup": "completion", "includeCommandLineAPI": true, "doNotPauseOnExceptionsAndMuteConsole": true, "returnByValue": false, "generatePreview": false, "saveResult": false, "emulateUserGesture": false } } [Log] response: { "result": { "result": { "type": "object", "objectId": "{\"injectedScriptId\":1,\"id\":4003}", "className": "BackForwardEntry", "description": "BackForwardEntry" } }, "id": 675 [Log] request: { "id": 701, "method": "Runtime.callFunctionOn", "params": { "objectId": "{\"injectedScriptId\":1,\"id\":4003}", "functionDeclaration": "\n//# sourceURL=__WebInspectorInternal__\nfunction inspectedPage_evalResult_getCompletions(primitiveType)\n {\n var object;\n if (primitiveType === \"string\")\n object = new String(\"\");\n else if (primitiveType === \"number\")\n object = new Number(0);\n else if (primitiveType === \"boolean\")\n object = new Boolean(false);\n else if (primitiveType === \"symbol\")\n object = Symbol();\n else\n object = this;\n\n var resultSet = {};\n for (var o = object; o; o = o.__proto__) {\n try {\n var names = Object.getOwnPropertyNames(o);\n for (var i = 0; i < names.length; ++i)\n resultSet[names[i]] = true;\n } catch (e) { }\n }\n\n return resultSet;\n }", "doNotPauseOnExceptionsAndMuteConsole": true, "returnByValue": true } } ... [Log] request: { "id": 703, "method": "Runtime.releaseObjectGroup", "params": { "objectGroup": "completion" } } ... [Log] response: { "error": { "code": -32000, "message": "Could not find object with given id", "data": [{ "code": -32000, "message": "Could not find object with given id" }] }, "id": 701 } 1570328 2 378667 joepeck 2019-09-12 12:27:53 -0700 Created attachment 378667 [PATCH] Proposed Fix 1570396 3 378667 hi 2019-09-12 15:26:18 -0700 Comment on attachment 378667 [PATCH] Proposed Fix View in context: https://bugs.webkit.org/attachment.cgi?id=378667&action=review r=me, nice! I've encountered this a handful of times but could never reproduce. Great catch! =D > Source/WebInspectorUI/UserInterface/Controllers/JavaScriptRuntimeCompletionProvider.js:378 > + this._ongoingCompletionRequests++; Style: `++this._ongoingCompletionRequests;` > Source/WebInspectorUI/UserInterface/Controllers/JavaScriptRuntimeCompletionProvider.js:381 > + _decrementOngoingCompletionRequests() Style: `--this._ongoingCompletionRequests;` > Source/WebInspectorUI/UserInterface/Controllers/JavaScriptRuntimeCompletionProvider.js:385 > + if (!this._ongoingCompletionRequests) We should assert that we haven't gone below `0` (and maybe even change the `if` condition to reflect that as well, given how many different branches this code has). 1570514 4 378667 joepeck 2019-09-13 00:21:20 -0700 Comment on attachment 378667 [PATCH] Proposed Fix View in context: https://bugs.webkit.org/attachment.cgi?id=378667&action=review >> Source/WebInspectorUI/UserInterface/Controllers/JavaScriptRuntimeCompletionProvider.js:378 >> + this._ongoingCompletionRequests++; > > Style: `++this._ongoingCompletionRequests;` There is no reason to prefer pre or post in JavaScript. We have hundreds of examples of each. I think readability should matter more and post is more readable in `this._member` cases, and our existing code seems to agree. >> Source/WebInspectorUI/UserInterface/Controllers/JavaScriptRuntimeCompletionProvider.js:385 >> + if (!this._ongoingCompletionRequests) > > We should assert that we haven't gone below `0` (and maybe even change the `if` condition to reflect that as well, given how many different branches this code has). Okay. It seems more likely that a decrement will be missed, in which case the counter ever increases, which is not easy to catch with assertions. 1570645 5 joepeck 2019-09-13 11:33:59 -0700 Source/WebInspectorUI/UserInterface/Controllers/JavaScriptRuntimeCompletionProvider.js:385 > >> + if (!this._ongoingCompletionRequests) > > > > We should assert that we haven't gone below `0` (and maybe even change the `if` condition to reflect that as well, given how many different branches this code has). > > Okay. It seems more likely that a decrement will be missed, in which case > the counter ever increases, which is not easy to catch with assertions. I think I'll add an assertion that we never get above 50. If so something has probably gone wrong and it would be useful to alert us of that in development! 1570658 6 joepeck 2019-09-13 11:58:49 -0700 https://trac.webkit.org/changeset/249846/webkit 1570659 7 webkit-bug-importer 2019-09-13 11:59:19 -0700 <rdar://problem/55347422> 378667 2019-09-12 12:27:53 -0700 2019-09-13 11:56:59 -0700 [PATCH] Proposed Fix completion-1.patch text/plain 4076 joepeck ZGlmZiAtLWdpdCBhL1NvdXJjZS9XZWJJbnNwZWN0b3JVSS9DaGFuZ2VMb2cgYi9Tb3VyY2UvV2Vi SW5zcGVjdG9yVUkvQ2hhbmdlTG9nCmluZGV4IDBjMDU2MGVkY2M3Li5mOWQ1YTI3ZGM5NyAxMDA2 NDQKLS0tIGEvU291cmNlL1dlYkluc3BlY3RvclVJL0NoYW5nZUxvZworKysgYi9Tb3VyY2UvV2Vi SW5zcGVjdG9yVUkvQ2hhbmdlTG9nCkBAIC0xLDMgKzEsMTcgQEAKKzIwMTktMDktMTIgIEpvc2Vw aCBQZWNvcmFybyAgPHBlY29yYXJvQGFwcGxlLmNvbT4KKworICAgICAgICBVbmNhdWdodCBFeGNl cHRpb246IG51bGwgaXMgbm90IGFuIG9iamVjdCAoZXZhbHVhdGluZyAnT2JqZWN0LmtleXMocHJv cGVydHlOYW1lcynigIsnKeKAiyAoYXQgSmF2YVNjcmlwdFJ1bnRpbWVDb21wbGV0aW9uUHJvdmlk 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