Build 32 seems to have an issue starting up.
$ snap run signal-desktop
Gtk-Message: Failed to load module "overlay-scrollbar"
Gtk-Message: Failed to load module "gail"
Gtk-Message: Failed to load module "atk-bridge"
Gtk-Message: Failed to load module "canberra-gtk-module"
NODE_ENV production
NODE_CONFIG_DIR /snap/signal-desktop/32/resources/app.asar/config
NODE_CONFIG {}
ALLOW_CONFIG_MUTATIONS undefined
HOSTNAME undefined
NODE_APP_INSTANCE undefined
SUPPRESS_NO_CONFIG_WARNING undefined
Set Windows Application User Model ID (AUMID) { appUserModelId: 'org.whispersystems.signal-desktop' }
userData: /home/user/snap/signal-desktop/32/.config/Signal
making app single instance
{"name":"log","hostname":"hostname","pid":3786,"level":30,"msg":"app ready","time":"2018-05-22T08:03:14.380Z","v":0}
{"name":"log","hostname":"hostname","pid":3786,"level":30,"msg":"Ensure attachments directory exists","time":"2018-05-22T08:03:14.386Z","v":0}
{"name":"log","hostname":"hostname","pid":3786,"level":30,"msg":"Initializing BrowserWindow config: {\"show\":true,\"width\":904,\"height\":692,\"minWidth\":640,\"minHeight\":360,\"autoHideMenuBar\":false,\"webPreferences\":{\"nodeIntegration\":false,\"preload\":\"/snap/signal-desktop/32/resources/app.asar/preload.js\"},\"icon\":\"/snap/signal-desktop/32/resources/app.asar/images/icon_256.png\",\"maximized\":false,\"x\":769,\"y\":269}","time":"2018-05-22T08:03:14.389Z","v":0}
Trace/breakpoint trap (core dumped)
log.log
only gives me:
{"name":"log","hostname":"hostname","pid":3786,"level":30,"msg":"app ready","time":"2018-05-22T08:03:14.380Z","v":0}
{"name":"log","hostname":"hostname","pid":3786,"level":30,"msg":"Ensure attachments directory exists","time":"2018-05-22T08:03:14.386Z","v":0}
Not sure where I would find this core dump.
The apt version does not have any issues right now.