The squeak install file was downloaded from:

pi@raspberrypi:~/Squeak5.3-19435-32bit-202003021730-ARMv6 $ ./squeak.sh
Using /home/pi/Squeak5.3-19435-32bit-202003021730-ARMv6/bin/squeak...
pthread_setschedparam failed: Operation not permitted
This VM uses a separate heartbeat thread to update its internal clock
and handle events.  For best operation, this thread should run at a
higher priority, however the VM was unable to change the priority.  The
effect is that heavily loaded systems may experience some latency
issues.  If this occurs, please create the appropriate configuration
file in /etc/security/limits.d/ as shown below:

cat <<END | sudo tee /etc/security/limits.d/squeak.conf
*      hard    rtprio  2
*      soft    rtprio  2
END

and report to the squeak mailing list whether this improves behaviour.

You will need to log out and log back in for the limits to take effect.
For more information please see
https://github.com/OpenSmalltalk/opensmalltalk-vm/releases/tag/r3732#linux

Recursive not understood error encountered

/home/pi/Squeak5.3-19435-32bit-202003021730-ARMv6/bin/squeak
Squeak VM version: 5.0-202003021730  Tue Mar  3 09:42:45 UTC 2020 gcc 4.9.2 [Production Spur VM]
Built from: CoInterpreter VMMaker.oscog-nice.2712 uuid: da64ef0b-fb0a-4770-ac16-f9b448234615 Mar  3 2020
With: StackToRegisterMappingCogit VMMaker.oscog-eem.2719 uuid: e40f3e94-3a54-411b-9613-5d19114ea131 Mar  3 2020
Revision: VM: 202003021730 https://github.com/OpenSmalltalk/opensmalltalk-vm.git
Date: Mon Mar 2 18:30:55 2020 CommitHash: 6a0bc96
Plugins: 202003021730 https://github.com/OpenSmalltalk/opensmalltalk-vm.git
Build host: Linux travis-job-97835d24-79f4-41d1-b7e9-c81bd8bf7149 4.4.0-104-generic #127~14.04.1-Ubuntu SMP Mon Dec 11 12:44:15 UTC 2017 armv7l GNU/Linux
plugin path: /home/pi/Squeak5.3-19435-32bit-202003021730-ARMv6/bin/ [default: /home/pi/Squeak5.3-19435-32bit-202003021730-ARMv6/bin/]


C stack backtrace & registers:
*[0x7e8a47fc]


Smalltalk stack dump:
0x7e8a67c0 I SmalltalkImage>setGCParameters 0xd3a9d0: a(n) SmalltalkImage
0x7e8a67e8 I SmalltalkImage>snapshot:andQuit:withExitCode:embedded: 0xd3a9d0: a(n) SmalltalkImage
 0x31d16d0 s SmalltalkImage>snapshot:andQuit:embedded:
 0x31d26f8 s SmalltalkImage>snapshot:andQuit:
 0x31d27b8 s [] in ReleaseBuilder class>saveAndQuit
 0x31d2890 s WorldState>runStepMethodsIn:
 0x31d2920 s PasteUpMorph>runStepMethods
 0x31d29f0 s WorldState>doOneCycleNowFor:
 0x31d2a50 s WorldState>doOneCycleFor:
 0x31d2ac0 s PasteUpMorph>doOneCycle
 0x31d2b20 s [] in MorphicProject>spawnNewProcess
 0x31d2b80 s [] in BlockClosure>newProcess

Most recent primitives
basicNew
size
at:
basicNew:
decompress:fromByteArray:at:
beCursorWithMask:
vmParameterAt:
fractionPart
truncated

stack page bytes 4096 available headroom 2788 minimum unused headroom 3740

(Recursive not understood error encountered)
Aborted