[OpenLayers-Users] Why does "OpenLayers.Layer.Vector" not work at all?

[Manuel Reimer]

Eric Lemoine wrote:
> It is unexpected. What version of OpenLayers are you using? Do you
> have a minimal example showing the problem?

I use the version accessible via
http://www.openlayers.org/api/OpenLayers.js

A "minimal example" could be something like example at the end of this 
mail, but my code is much more complex and I didn't test if this reduced 
code actually works. I placed the "OpenLayers.js" in the same directory 
as my HTML to get sure I don't get problems with "same origin policy".

I tried several things to debug, but OpenLayers seems to "catch and 
drop" any errors, which started to suck at some point. It would be much 
more helpful if OpenLayers would cause JS exceptions to cancel script 
execution and add a log entry to the Error Console in Firefox. Another 
problem is the "compressed" OpenLayers.js. Unreadable and (at least for 
me) impossible to debug.

Reduced sample follows:

   map = new OpenLayers.Map("map", {
     projection: new OpenLayers.Projection("EPSG:900913"),
     displayProjection: new OpenLayers.Projection("EPSG:4326"),
     controls: [
       new OpenLayers.Control.MouseDefaults(),
       new OpenLayers.Control.Attribution()],
     maxExtent: new OpenLayers.Bounds(-20037508.34,-20037508.34,
                                       20037508.34, 20037508.34),
     numZoomLevels: 18,
     maxResolution: 156543,
     units: "meters"
   });

   map.addControl(new OpenLayers.Control.Permalink("permalink"));
   map.addControl(new OpenLayers.Control.MousePosition());
   map.addControl(new OpenLayers.Control.PanZoomBar());

   layer_layerMapnik = new OpenLayers.Layer.OSM.Mapnik("Mapnik");
   map.addLayer(layer_layerMapnik)

var layer = new OpenLayers.Layer.Vector("Polygon", {
   strategies: [new OpenLayers.Strategy.Fixed()],
   protocol: new OpenLayers.Protocol.HTTP({
     url: "relation.osm",
     format: new OpenLayers.Format.OSM()
   }),
   projection: map.displayProjection, //new 
OpenLayers.Projection("EPSG:4326"),
   style: {strokeColor: "green", strokeWidth: 5, strokeOpacity: 0.5}
});
map.addLayer(layer);