Errors with IE11, in hypergrid

[voltcode]

using https://jpmorganchase.github.io/perspective/examples/superstore.html in IE 11,

scenario:

1. switch to grid mode
2. unselect country and city
3. move country to columns, after sub-category

results:

1. it's veeery slow - is it because of perspective or because of hypergrid?
2. console shows:
   SCRIPT5022: Assertion failed
   webcomponents.min.js (11,1555)
   View cancelled
   View cancelled
   Setting up initial schema and data load into HyperGrid

that's probably indicating an internal fault?

[texodus]

Thanks for the detailed report, this is very helpful.

This is indeed an internal fault. The only way to get real diagnostics in this case is to re-build the library with debug flags, which is currently a bit painful to configure. I will try to repro.

IE11 will always lag in performance to modern browsers, but we intend to support it functionally until it is dead and buried in industry.

[texodus]

I've tested this on the copy of IE11 I have, and only seen out-of-memory errors on large data sets - but this should come with an associated error more detailed than "Assertion Failed."

I've added a build option to generate a debug build, which should give you more information about such issues. Can you please try running a build as below, and filing a separate report with the stack trace if you encounter any issues?

`PSP_DEBUG=1 npm start`