improve pdfjs error reporting: Error rendering canvas page: [object Object]

[haraldschilly]

I don't know what is going on. It's a *.tex file and the error isn't really showing up. At least, this should be reported in a better way and not Error rendering canvas page: [object Object]. The file in question is smc-webapp/frame-editors/latex-editor/pdfjs-canvas-page.tsx

---

chrome: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/64.0.3282.140 Safari/537.36 Edge/17.17134

smc_git_rev: 5fbcfd0

Date: 2019-02-11 11:31:56.228612

{"0":"pdf.js -- Error rendering canvas page: [object Object]"}

<generated>
Error
   at s (https://cocalc.com/static/smc-175fc602124e4d629368.cacheme.js?175fc602124e4d629368:5:701345)
   at m (https://cocalc.com/static/smc-175fc602124e4d629368.cacheme.js?175fc602124e4d629368:5:703780)
   at Anonymous function (https://cocalc.com/static/smc-175fc602124e4d629368.cacheme.js?175fc602124e4d629368:5:704261)
   at e[t] (https://cocalc.com/static/smc-175fc602124e4d629368.cacheme.js?175fc602124e4d629368:5:704068)
   at Anonymous function (https://cocalc.com/static/smc-175fc602124e4d629368.cacheme.js?175fc602124e4d629368:5:2309355)
   at Anonymous function (https://cocalc.com/static/smc-175fc602124e4d629368.cacheme.js?175fc602124e4d629368:5:2308323)
   at Anonymous function (https://cocalc.com/static/smc-175fc602124e4d629368.cacheme.js?175fc602124e4d629368:5:2307636)
   at s (https://cocalc.com/static/smc-175fc602124e4d629368.cacheme.js?175fc602124e4d629368:5:2307244)

[williamstein]

This motivated #3559