On 10 June 2017 at 17:22, Sam Ruby <ru...@intertwingly.net> wrote: > On Sat, Jun 10, 2017 at 12:05 PM, sebb <seb...@gmail.com> wrote: >> On 10 June 2017 at 16:58, Sam Ruby <ru...@intertwingly.net> wrote: >>> On Sat, Jun 10, 2017 at 11:48 AM, sebb <seb...@gmail.com> wrote: >>>> On 10 June 2017 at 15:57, Sam Ruby <ru...@intertwingly.net> wrote: >>>>> On Sat, Jun 10, 2017 at 10:27 AM, sebb <seb...@gmail.com> wrote: >>>>>> On 10 June 2017 at 15:20, Sam Ruby <ru...@intertwingly.net> wrote: >>>>>>> On Sat, Jun 10, 2017 at 9:43 AM, sebb <seb...@gmail.com> wrote: >>>>>>>> Hard to trace entry in error.log: >>>>>>>> >>>>>>>> App 11526 stderr: _ERROR TypeError: Cannot read property 'proposal' of >>>>>>>> null >>>>>>>> >>>>>>>> The above error was fixed by cf054fd >>>>>>>> >>>>>>>> However finding the location of the error is not trivial, as there is >>>>>>>> no obvious context. >>>>>>>> >>>>>>>> Most other Ruby errors are reported with a stack trace and line >>>>>>>> numbers - why is this error different? >>>>>>>> Can it be fixed to produce a more detailed error message? >>>>>>> >>>>>>> It is different in that it actually is a JavaScript error. >>>>>>> >>>>>>> A number of whimsy applications use react.js in a number of pages >>>>>>> (many roster pages, all board agenda pages). If you view source on >>>>>>> those pages, you will see a static rendering, then the loading of >>>>>>> javascript files, then the data the scripts need. >>>>>>> >>>>>>> The static rendering is done by running the JavaScript application on >>>>>>> the server and inserting its output into the page. That application >>>>>>> may fail, which is what happened here. >>>>>> >>>>>> Can't such errors be caught by the code that runs JavaScript? >>>>> >>>>> I suspect that that would either require a change to ExecJS or for >>>>> Wunderbar to use an alternative to ExecJS. Here is the relevant >>>>> Wunderbar code: >>>>> >>>>> https://github.com/rubys/wunderbar/blob/master/lib/wunderbar/react.rb#L125 >>>> >>>> There's a rescue clause here: >>>> >>>> https://github.com/rubys/wunderbar/blob/master/lib/wunderbar/react.rb#L133 >>>> >>>> Is that catching all possible errors, or are some not catchable here? >>> >>> It is catching the error, and printing out the one line you are >>> seeing. What is missing is anything resembling a stack traceback - >>> which I presumed was the context you were originally looking for (see >>> subject line?). >> >> Yes. >> >> If Wunderbar has control over what is printed, then surely it can add >> some more context? >> Eg the name of the file it is processing? > > I'm still not following. > > In the case of the Roster tool, here's the input: > > https://github.com/apache/whimsy/blob/master/www/roster/views/ppmc.html.rb
This is not obvious from the error log > So, the name of the file being processed is 'app.js'. Here it is: > > https://github.com/apache/whimsy/blob/master/www/roster/views/app.js.rb > > Here's the generated javascript, which is run on both the client and server: > > https://whimsy.apache.org/roster/app.js > > The error you saw occurred some place in that generated file. > > It is not clear to me how logging the name 'app.js' would help with debugging. > > Knowing the page that failed would be more useful, but that already is > in the log. Is it? A sample log extract shows: App 11526 stderr: 71.168.148.85 - johndament [10/Jun/2017:12:35:34 +0000] "GET / HTTP/1.1" 304 - 1.6687 App 11526 stderr: 71.168.148.85 - johndament [10/Jun/2017:12:35:36 +0000] "GET /ppmc/ HTTP/1.1" 200 - 0.1865 App 11526 stderr: _ERROR TypeError: Cannot read property 'proposal' of null App 11526 stderr: 71.168.148.85 - johndament [10/Jun/2017:12:35:40 +0000] "GET /ppmc/ariatosca HTTP/1.1" 200 - 1.8059 App 11526 stderr: 71.168.148.85 - johndament [10/Jun/2017:12:35:40 +0000] "GET /app.js HTTP/1.1" 200 - 0.0036 App 11526 stderr: 71.168.148.85 - johndament [10/Jun/2017:12:54:49 +0000] "GET / HTTP/1.1" 304 - 1.3152 App 11526 stderr: 71.168.148.85 - johndament [10/Jun/2017:12:54:53 +0000] "GET /ppmc/ HTTP/1.1" 304 - 0.1825 App 11526 stderr: _ERROR TypeError: Cannot read property 'proposal' of null App 11526 stderr: 71.168.148.85 - johndament [10/Jun/2017:12:54:55 +0000] "GET /ppmc/ariatosca HTTP/1.1" 304 - 1.0298 App 11526 stderr: 71.168.148.85 - johndament [10/Jun/2017:12:54:56 +0000] "GET /app.js HTTP/1.1" 304 - 0.0004 App 11526 stderr: _ERROR TypeError: Cannot read property 'proposal' of null App 11526 stderr: 98.122.169.124 - rubys [10/Jun/2017:13:02:40 +0000] "GET /ppmc/atlas HTTP/1.1" 200 - 0.5462 App 11526 stderr: 98.122.169.124 - rubys [10/Jun/2017:13:02:41 +0000] "GET /stylesheets/app.css HTTP/1.1" 200 - 0.0007 App 11526 stderr: 98.122.169.124 - rubys [10/Jun/2017:13:02:41 +0000] "GET /app.js HTTP/1.1" 200 - 0.0032 It's not at all obvious how to debug that, except that it is probably associated with the /ppmc/ URL There's no indication that the error is a Javascript error. Nor how to find the script that generated the Javascript When I tried forcing an error, the Javascript console shows: Uncaught TypeError: Cannot read property 'length' of undefined at main.js.rb:144 .... But the screen only shows 'TypeError: Cannot read property 'length' of undefined' and the log likewise. I would expect the log (and possibly the screen) to show the first part of the stack trace. > - Sam Ruby > >>> Or am I misunderstanding what you are looking for? >>> >>>>>>> Generally, the easiest way to debug such situations is to bring the >>>>>>> page up in the browser and look at the error console. It used to be >>>>>>> the case that in both Firefox and Chrome, you could click on the stack >>>>>>> traceback in the console to see the original source; but for reasons I >>>>>>> don't understand, with the current FIrefox you see the generated >>>>>>> JavaScript instead. >>>>>>> >>>>>>> - Sam Ruby >>>>> >>>>> - Sam Ruby >>> >>> - Sam Ruby
