simplifies code for promise handling for DVID mesh support
simplifies code for promise handling for DVID mesh support

seung-lab/neuroglancer,google/neuroglancer,janelia-flyem/neuroglancer,seung-lab/neuroglancer,janelia-flyem/neuroglancer,seung-lab/neuroglancer,seung-lab/neuroglancer,google/neuroglancer,google/neuroglancer,google/neuroglancer,janelia-flyem/neuroglancer,seung-lab/neuroglancer,google/neuroglancer,google/neuroglancer,janelia-flyem/neuroglancer,google/neuroglancer,seung-lab/neuroglancer,seung-lab/neuroglancer,google/neuroglancer,janelia-flyem/neuroglancer