getProgramParameter(program, parallelShaderCompileExt.COMPLETION_STATUS_KHR) fails incorrectly on a restored WebGLContext

[WesselKroos]

The first time a WebGLContext is created this goes correctly. But when a lost WebGLContext was restored by Chrome and I'm getting the COMPLETION_STATUS_KHR program parameter the following error message is thrown:
error in getProgramParameter(WebGLProgram("*UNTAGGED:Program4*"), COMPLETION_STATUS_KHR): INVALID_ENUM

The extension is enabled because getExtension('KHR_parallel_shader_compile').COMPLETION_STATUS_KHR is 37297.

My code:

const parallelShaderCompileExt = gl.getExtension('KHR_parallel_shader_compile');
if(parallelShaderCompileExt) {
  let completed = gl.getProgramParameter(program, parallelShaderCompileExt.COMPLETION_STATUS_KHR);
  // ...
}