the result of heroku logs --tail

   Warning: heroku update available from 7.38.2 to 7.42.6.
2020-08-12T22:32:51.450396+00:00 app[web.1]: npm ERR! errno ENOENT
2020-08-12T22:32:51.452680+00:00 app[web.1]: npm ERR! [email protected] start: `serve -s build`    
2020-08-12T22:32:51.452896+00:00 app[web.1]: npm ERR! spawn ENOENT
2020-08-12T22:32:51.453058+00:00 app[web.1]: npm ERR!
2020-08-12T22:32:51.453205+00:00 app[web.1]: npm ERR! Failed at the [email protected] start script.
2020-08-12T22:32:51.453348+00:00 app[web.1]: npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
2020-08-12T22:32:51.467442+00:00 app[web.1]: 
2020-08-12T22:32:51.467627+00:00 app[web.1]: npm ERR! A complete log of this run can be found in:
2020-08-12T22:32:51.467740+00:00 app[web.1]: npm ERR!     /app/.npm/_logs/2020-08-12T22_32_51_460Z-debug.log
2020-08-12T22:32:51.556136+00:00 heroku[web.1]: Process exited with status 1
2020-08-12T22:32:51.706650+00:00 heroku[web.1]: State changed from starting to crashed   
2020-08-13T00:12:06.031766+00:00 heroku[web.1]: State changed from crashed to starting   
2020-08-13T00:12:29.908831+00:00 heroku[web.1]: Starting process with command `npm start`
2020-08-13T00:12:34.256591+00:00 app[web.1]: 
2020-08-13T00:12:34.256605+00:00 app[web.1]: > [email protected] start /app
2020-08-13T00:12:34.256606+00:00 app[web.1]: > serve -s build
2020-08-13T00:12:34.256606+00:00 app[web.1]: 
2020-08-13T00:12:34.267835+00:00 app[web.1]: sh: 1: serve: not found
2020-08-13T00:12:34.277638+00:00 app[web.1]: npm ERR! code ELIFECYCLE
2020-08-13T00:12:34.277976+00:00 app[web.1]: npm ERR! syscall spawn
2020-08-13T00:12:34.278160+00:00 app[web.1]: npm ERR! file sh
2020-08-13T00:12:34.278407+00:00 app[web.1]: npm ERR! errno ENOENT
2020-08-13T00:12:34.282374+00:00 app[web.1]: npm ERR! [email protected] start: `serve -s build`
2020-08-13T00:12:34.282530+00:00 app[web.1]: npm ERR! spawn ENOENT
2020-08-13T00:12:34.282714+00:00 app[web.1]: npm ERR!
2020-08-13T00:12:34.282893+00:00 app[web.1]: npm ERR! Failed at the [email protected] start script.
2020-08-13T00:12:34.283046+00:00 app[web.1]: npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
2020-08-13T00:12:34.674667+00:00 app[web.1]: 
2020-08-13T00:12:34.674916+00:00 app[web.1]: npm ERR! A complete log of this run can be found in:
2020-08-13T00:12:34.675120+00:00 app[web.1]: npm ERR!     /app/.npm/_logs/2020-08-13T00_12_34_294Z-debug.log
2020-08-13T00:12:34.767444+00:00 heroku[web.1]: Process exited with status 1
2020-08-13T00:12:34.824549+00:00 heroku[web.1]: State changed from starting to crashed
2020-08-13T03:16:16.841659+00:00 heroku[web.1]: State changed from crashed to starting
2020-08-13T03:16:35.468567+00:00 heroku[web.1]: Starting process with command `npm start`
2020-08-13T03:16:38.157607+00:00 app[web.1]:
2020-08-13T03:16:38.157622+00:00 app[web.1]: > [email protected] start /app
2020-08-13T03:16:38.157622+00:00 app[web.1]: > serve -s build
2020-08-13T03:16:38.157623+00:00 app[web.1]:
2020-08-13T03:16:38.165381+00:00 app[web.1]: sh: 1: serve: not found
2020-08-13T03:16:38.172471+00:00 app[web.1]: npm ERR! code ELIFECYCLE
2020-08-13T03:16:38.172929+00:00 app[web.1]: npm ERR! syscall spawn
2020-08-13T03:16:38.173178+00:00 app[web.1]: npm ERR! file sh
2020-08-13T03:16:38.173507+00:00 app[web.1]: npm ERR! errno ENOENT
2020-08-13T03:16:38.177380+00:00 app[web.1]: npm ERR! [email protected] start: `serve -s build`
2020-08-13T03:16:38.177600+00:00 app[web.1]: npm ERR! spawn ENOENT
2020-08-13T03:16:38.177862+00:00 app[web.1]: npm ERR!
2020-08-13T03:16:38.178103+00:00 app[web.1]: npm ERR! Failed at the [email protected] start script.
2020-08-13T03:16:38.178292+00:00 app[web.1]: npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
2020-08-13T03:16:38.197267+00:00 app[web.1]:
2020-08-13T03:16:38.197543+00:00 app[web.1]: npm ERR! A complete log of this run can be found in:
2020-08-13T03:16:38.197729+00:00 app[web.1]: npm ERR!     /app/.npm/_logs/2020-08-13T03_16_38_189Z-debug.log
2020-08-13T03:16:38.257872+00:00 heroku[web.1]: Process exited with status 1
2020-08-13T03:16:38.294877+00:00 heroku[web.1]: State changed from starting to crashed
2020-08-13T07:28:25.131652+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/" host=amazz-movie-timeline.herokuapp.com request_id=25669c31-e035-4959-8dd3-93176044818d fwd="146.185.34.212" dyno= connect= service= status=503 bytes= protocol=http
2020-08-13T07:28:26.580915+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/favicon.ico" host=amazz-movie-timeline.herokuapp.com request_id=0002d326-d3e0-4f6c-b53e-b070f07d9434 fwd="146.185.34.212" dyno= connect= service= status=503 bytes= protocol=http
2020-08-13T07:32:06.554093+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=HEAD path="/" host=amazz-movie-timeline.herokuapp.com request_id=25f44e74-c252-467e-ae85-04a3abb60bd4 fwd="217.182.175.162" dyno= connect= service= status=503 bytes= protocol=http
2020-08-13T07:56:45.375609+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/" host=amazz-movie-timeline.herokuapp.com request_id=8aa4b501-8897-44e0-b0fa-3f89efc1ca12 fwd="41.210.146.52" dyno= connect= service= status=503 bytes= protocol=http
2020-08-13T07:56:48.714296+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/favicon.ico" host=amazz-movie-timeline.herokuapp.com request_id=fa4824a4-65c4-4386-a2d3-e8b15bed4874 fwd="41.210.146.52" dyno= connect= service= status=503 bytes= protocol=http
2020-08-13T08:38:43.921509+00:00 heroku[web.1]: State changed from crashed to starting
2020-08-13T08:38:57.561021+00:00 heroku[web.1]: Starting process with command `npm start`
2020-08-13T08:38:59.911703+00:00 app[web.1]:
2020-08-13T08:38:59.911721+00:00 app[web.1]: > [email protected] start /app
2020-08-13T08:38:59.911722+00:00 app[web.1]: > serve -s build
2020-08-13T08:38:59.911722+00:00 app[web.1]:
2020-08-13T08:38:59.917110+00:00 app[web.1]: sh: 1: serve: not found
2020-08-13T08:38:59.921892+00:00 app[web.1]: npm ERR! code ELIFECYCLE
2020-08-13T08:38:59.922157+00:00 app[web.1]: npm ERR! syscall spawn
2020-08-13T08:38:59.922360+00:00 app[web.1]: npm ERR! file sh
2020-08-13T08:38:59.922599+00:00 app[web.1]: npm ERR! errno ENOENT
2020-08-13T08:38:59.924661+00:00 app[web.1]: npm ERR! [email protected] start: `serve -s build`
2020-08-13T08:38:59.924793+00:00 app[web.1]: npm ERR! spawn ENOENT
2020-08-13T08:38:59.924939+00:00 app[web.1]: npm ERR!
2020-08-13T08:38:59.925125+00:00 app[web.1]: npm ERR! Failed at the [email protected] start script.
2020-08-13T08:38:59.925261+00:00 app[web.1]: npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
2020-08-13T08:38:59.933451+00:00 app[web.1]:
2020-08-13T08:38:59.933634+00:00 app[web.1]: npm ERR! A complete log of this run can be found in:
2020-08-13T08:38:59.933754+00:00 app[web.1]: npm ERR!     /app/.npm/_logs/2020-08-13T08_38_59_926Z-debug.log
2020-08-13T08:38:59.992472+00:00 heroku[web.1]: Process exited with status 1
2020-08-13T08:39:00.039370+00:00 heroku[web.1]: State changed from starting to crashed
2020-08-13T14:51:27.376688+00:00 heroku[web.1]: State changed from crashed to starting
2020-08-13T14:51:41.558458+00:00 heroku[web.1]: Starting process with command `npm start`
2020-08-13T14:51:44.129603+00:00 app[web.1]:
2020-08-13T14:51:44.129619+00:00 app[web.1]: > [email protected] start /app
2020-08-13T14:51:44.129619+00:00 app[web.1]: > serve -s build
2020-08-13T14:51:44.129620+00:00 app[web.1]: 
2020-08-13T14:51:44.140913+00:00 app[web.1]: sh: 1: serve: not found
2020-08-13T14:51:44.146473+00:00 app[web.1]: npm ERR! code ELIFECYCLE
2020-08-13T14:51:44.146839+00:00 app[web.1]: npm ERR! syscall spawn
2020-08-13T14:51:44.147189+00:00 app[web.1]: npm ERR! file sh
2020-08-13T14:51:44.147532+00:00 app[web.1]: npm ERR! errno ENOENT
2020-08-13T14:51:44.151356+00:00 app[web.1]: npm ERR! [email protected] start: `serve -s build`
2020-08-13T14:51:44.151560+00:00 app[web.1]: npm ERR! spawn ENOENT
2020-08-13T14:51:44.151815+00:00 app[web.1]: npm ERR!
2020-08-13T14:51:44.152024+00:00 app[web.1]: npm ERR! Failed at the [email protected] start script.
2020-08-13T14:51:44.152225+00:00 app[web.1]: npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
2020-08-13T14:51:44.179555+00:00 app[web.1]:
2020-08-13T14:51:44.183945+00:00 app[web.1]: npm ERR! A complete log of this run can be found in:
2020-08-13T14:51:44.184152+00:00 app[web.1]: npm ERR!     /app/.npm/_logs/2020-08-13T14_51_44_154Z-debug.log
2020-08-13T14:51:44.262438+00:00 heroku[web.1]: Process exited with status 1
2020-08-13T14:51:44.317242+00:00 heroku[web.1]: State changed from starting to crashed