message: check if WEBGL_depth_texture is supported
diff: @@ -238,6 +238,10 @@ export function createTexture(gl: GLRenderingContext, extensions: WebGLExtension
  throw new Error(`texture kind '${kind}' and type '${_type}' are incompatible`);
  }
  + if (!extensions.depthTexture && _format === 'depth') {
  + throw new Error(`extension 'WEBGL_depth_texture' needed for 'depth' texture format`);
  + }
  +
  const target = getTarget(gl, kind);
  const filter = getFilter(gl, _filter);
  const format = getFormat(gl, _format, _type);
  