ol.proj.transform when moving from 4.6.5 to 5.3.0

[andrewteg]

When ol.proj.transform for a proj4 defined projection I get an error of "of Uncaught TypeError: Cannot read property 'getCode' of null on the transform line." on 5.3.0 but it works fine if I roll back to v4.6.5.

To Reproduce

1. Go to https://jsfiddle.net/rjapzgfd/
2. See the transformed coordinate.
3. Change the ol.js Resource from 4.6.5 to 5.3.0 and re-run.
4. Get a dev console error of "Uncaught TypeError: Cannot read property 'getCode' of null on the transform line."

Expected behavior
This code should still work in 5.3.0 or have a suitable replacement (which I cannot find in the docs):

proj4.defs("EPSG:2284","+proj=lcc +lat_1=37.96666666666667 +lat_2=36.76666666666667 +lat_0=36.33333333333334 +lon_0=-78.5 +x_0=3500000.0001016 +y_0=999999.9998983998 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=us-ft +no_defs");

var test_coordinate = ol.proj.transform([-79.4460,37.7890], 'EPSG:4326', 'EPSG:2284');
console.log(test_coordinate);
document.getElementById("demo").innerHTML = test_coordinate; //transformed!

[ahocevar]

Please always check the release notes when making a major release upgrade:

Applications can be updated by importing the register function from the ol/proj/proj4 module

import {register} from 'ol/proj/proj4'

and calling it before using projections, and any time the proj4 registry was changed by proj4.defs() calls:

register(proj4);

So you have to call

ol.proj.proj4.register(proj4);

before working with projections.

I have update your fiddle with this change: https://jsfiddle.net/dtyrws39/.

[andrewteg]

Thanks, sorry to trouble you {goes for caffeine to re-brush up on release notes}!