openlayers: Map freezing when pinch zooming on ipad

We are getting this error on IOS 10.3.2 on safari, trying to migrate an app from 3.19.1 to 4.1.1, and when making fast pinch zoom in and out. All the map disappear (only the overlays stay there) and the map freeze completely.

We also get this unhandled exception from webkit : DOM Exception 11 : The object is in an invalid state

From the stack trace (of the minified code) the offending line is the drawImage() call from this function : function qv(a) { zt.call(this, a); this.u = yh(); this.j = null } u(qv, zt); qv.prototype.O = function (a, b, c) { Bt(this, "precompose", c, a, void 0); var d = this.Y(); if (d) { var e = b.extent, f = void 0 !== e && !Ua(e, a.extent) && nb(e, a.extent); f && At(c, a, e); var e = this.A(), g = c.globalAlpha; c.globalAlpha = b.opacity; c.drawImage(d, 0, 0, +d.width, +d.height, Math.round(e[4]), Math.round(e[5]), Math.round(d.width * e[0]), Math.round(d.height * e[3])); c.globalAlpha = g; f && c.restore() } this.cf(c, a, b) };

For now i’m unable to repro this in a jsfiddle.