py: Clean up some logic in VM to remove assert(0)'s.
py: Clean up some logic in VM to remove assert(0)'s.

Saves around 30 bytes code on Thumb2 archs.

torwag/micropython,swegener/micropython,TDAbboud/micropython,ericsnowcurrently/micropython,blmorris/micropython,heisewangluo/micropython,infinnovation/micropython,mianos/micropython,ruffy91/micropython,puuu/micropython,ceramos/micropython,alex-robbins/micropython,pfalcon/micropython,xyb/micropython,alex-march/micropython,neilh10/micropython,HenrikSolver/micropython,adafruit/circuitpython,PappaPeppar/micropython,suda/micropython,jmarcelino/pycom-micropython,martinribelotta/micropython,MrSurly/micropython-esp32,ericsnowcurrently/micropython,hiway/micropython,pozetroninc/micropython,omtinez/micropython,omtinez/micropython,micropython/micropython-esp32,noahwilliamsson/micropython,PappaPeppar/micropython,jlillest/micropython,skybird6672/micropython,paul-xxx/micropython,oopy/micropython,EcmaXp/micropython,rubencabrera/micropython,feilongfl/micropython,slzatz/micropython,noahchense/micropython,martinribelotta/micropython,pozetroninc/micropython,firstval/micropython,chrisdearman/micropython,henriknelson/micropython,dinau/micropython,swegener/micropython,ganshun666/micropython,pfalcon/micropython,ruffy91/micropython,bvernoux/micropython,drrk/micropython,slzatz/micropython,firstval/micropython,jmarcelino/pycom-micropython,alex-march/micropython,dhylands/micropython,infinnovation/micropython,emfcamp/micropython,EcmaXp/micropython,omtinez/micropython,cwyark/micropython,toolmacher/micropython,stonegithubs/micropython,alex-robbins/micropython,alex-robbins/micropython,martinribelotta/micropython,ChuckM/micropython,cwyark/micropython,trezor/micropython,rubencabrera/micropython,redbear/micropython,martinribelotta/micropython,dxxb/micropython,paul-xxx/micropython,HenrikSolver/micropython,blmorris/micropython,misterdanb/micropython,cloudformdesign/micropython,feilongfl/micropython,xhat/micropython,HenrikSolver/micropython,dinau/micropython,misterdanb/micropython,dxxb/micropython,kostyll/micropython,bvernoux/micropython,pramasoul/micropython,feilongfl/micropython,henriknelson/micropython,warner83/micropython,MrSurly/micropython,TDAbboud/micropython,jlillest/micropython,ernesto-g/micropython,blazewicz/micropython,neilh10/micropython,Peetz0r/micropython-esp32,cwyark/micropython,mianos/micropython,toolmacher/micropython,praemdonck/micropython,pozetroninc/micropython,oopy/micropython,hosaka/micropython,adafruit/circuitpython,dhylands/micropython,vriera/micropython,adafruit/micropython,stonegithubs/micropython,tuc-osg/micropython,tdautc19841202/micropython,tdautc19841202/micropython,pramasoul/micropython,redbear/micropython,trezor/micropython,hiway/micropython,drrk/micropython,MrSurly/micropython,noahwilliamsson/micropython,matthewelse/micropython,TDAbboud/micropython,vitiral/micropython,MrSurly/micropython,neilh10/micropython,hiway/micropython,mhoffma/micropython,mgyenik/micropython,jimkmc/micropython,dmazzella/micropython,mgyenik/micropython,chrisdearman/micropython,deshipu/micropython,toolmacher/micropython,swegener/micropython,dmazzella/micropython,mgyenik/micropython,noahchense/micropython,TDAbboud/micropython,kerneltask/micropython,xhat/micropython,dmazzella/micropython,MrSurly/micropython-esp32,orionrobots/micropython,ceramos/micropython,turbinenreiter/micropython,redbear/micropython,tobbad/micropython,heisewangluo/micropython,mpalomer/micropython,supergis/micropython,MrSurly/micropython,galenhz/micropython,kerneltask/micropython,ernesto-g/micropython,dinau/micropython,tobbad/micropython,danicampora/micropython,blmorris/micropython,blmorris/micropython,micropython/micropython-esp32,praemdonck/micropython,kostyll/micropython,turbinenreiter/micropython,puuu/micropython,torwag/micropython,cloudformdesign/micropython,tralamazza/micropython,ahotam/micropython,ryannathans/micropython,xhat/micropython,tuc-osg/micropython,SHA2017-badge/micropython-esp32,kerneltask/micropython,adafruit/micropython,cnoviello/micropython,xhat/micropython,xuxiaoxin/micropython,ahotam/micropython,danicampora/micropython,noahchense/micropython,deshipu/micropython,henriknelson/micropython,selste/micropython,chrisdearman/micropython,henriknelson/micropython,torwag/micropython,pfalcon/micropython,tuc-osg/micropython,adafruit/micropython,danicampora/micropython,rubencabrera/micropython,mhoffma/micropython,utopiaprince/micropython,lbattraw/micropython,ruffy91/micropython,dinau/micropython,Timmenem/micropython,tralamazza/micropython,oopy/micropython,lbattraw/micropython,chrisdearman/micropython,trezor/micropython,stonegithubs/micropython,pramasoul/micropython,alex-robbins/micropython,MrSurly/micropython-esp32,heisewangluo/micropython,ryannathans/micropython,pramasoul/micropython,tobbad/micropython,blazewicz/micropython,tobbad/micropython,mhoffma/micropython,blazewicz/micropython,neilh10/micropython,Peetz0r/micropython-esp32,skybird6672/micropython,dhylands/micropython,ganshun666/micropython,mpalomer/micropython,dxxb/micropython,tralamazza/micropython,EcmaXp/micropython,warner83/micropython,xyb/micropython,EcmaXp/micropython,HenrikSolver/micropython,SHA2017-badge/micropython-esp32,mgyenik/micropython,vitiral/micropython,jmarcelino/pycom-micropython,praemdonck/micropython,ahotam/micropython,dhylands/micropython,feilongfl/micropython,dxxb/micropython,AriZuu/micropython,emfcamp/micropython,xhat/micropython,noahwilliamsson/micropython,xyb/micropython,martinribelotta/micropython,ceramos/micropython,bvernoux/micropython,lowRISC/micropython,puuu/micropython,ahotam/micropython,alex-march/micropython,tdautc19841202/micropython,adamkh/micropython,PappaPeppar/micropython,suda/micropython,hosaka/micropython,trezor/micropython,orionrobots/micropython,praemdonck/micropython,Timmenem/micropython,swegener/micropython,ganshun666/micropython,stonegithubs/micropython,PappaPeppar/micropython,ernesto-g/micropython,galenhz/micropython,ericsnowcurrently/micropython,mianos/micropython,emfcamp/micropython,suda/micropython,deshipu/micropython,ceramos/micropython,chrisdearman/micropython,selste/micropython,lowRISC/micropython,puuu/micropython,rubencabrera/micropython,pozetroninc/micropython,utopiaprince/micropython,infinnovation/micropython,dhylands/micropython,utopiaprince/micropython,hiway/micropython,AriZuu/micropython,cloudformdesign/micropython,warner83/micropython,ryannathans/micropython,orionrobots/micropython,alex-march/micropython,slzatz/micropython,paul-xxx/micropython,pfalcon/micropython,misterdanb/micropython,adamkh/micropython,mpalomer/micropython,utopiaprince/micropython,torwag/micropython,praemdonck/micropython,AriZuu/micropython,oopy/micropython,supergis/micropython,orionrobots/micropython,toolmacher/micropython,turbinenreiter/micropython,vitiral/micropython,vriera/micropython,supergis/micropython,MrSurly/micropython,mianos/micropython,firstval/micropython,Peetz0r/micropython-esp32,SHA2017-badge/micropython-esp32,orionrobots/micropython,ericsnowcurrently/micropython,lbattraw/micropython,turbinenreiter/micropython,vriera/micropython,galenhz/micropython,toolmacher/micropython,hiway/micropython,tuc-osg/micropython,ernesto-g/micropython,matthewelse/micropython,blmorris/micropython,pozetroninc/micropython,ryannathans/micropython,dinau/micropython,kerneltask/micropython,xuxiaoxin/micropython,hosaka/micropython,EcmaXp/micropython,warner83/micropython,mianos/micropython,paul-xxx/micropython,alex-robbins/micropython,selste/micropython,tralamazza/micropython,supergis/micropython,lbattraw/micropython,pramasoul/micropython,trezor/micropython,omtinez/micropython,jlillest/micropython,micropython/micropython-esp32,redbear/micropython,vriera/micropython,adafruit/circuitpython,tdautc19841202/micropython,misterdanb/micropython,feilongfl/micropython,ChuckM/micropython,utopiaprince/micropython,swegener/micropython,dmazzella/micropython,cloudformdesign/micropython,ganshun666/micropython,torwag/micropython,adafruit/circuitpython,ericsnowcurrently/micropython,mhoffma/micropython,skybird6672/micropython,selste/micropython,blazewicz/micropython,noahwilliamsson/micropython,skybird6672/micropython,ChuckM/micropython,suda/micropython,kostyll/micropython,tuc-osg/micropython,ganshun666/micropython,SHA2017-badge/micropython-esp32,Peetz0r/micropython-esp32,danicampora/micropython,jlillest/micropython,kostyll/micropython,drrk/micropython,mpalomer/micropython,mgyenik/micropython,ruffy91/micropython,jmarcelino/pycom-micropython,adamkh/micropython,ruffy91/micropython,emfcamp/micropython,AriZuu/micropython,skybird6672/micropython,micropython/micropython-esp32,drrk/micropython,Peetz0r/micropython-esp32,heisewangluo/micropython,paul-xxx/micropython,firstval/micropython,lowRISC/micropython,infinnovation/micropython,cnoviello/micropython,cwyark/micropython,kerneltask/micropython,jimkmc/micropython,deshipu/micropython,matthewelse/micropython,turbinenreiter/micropython,warner83/micropython,TDAbboud/micropython,SHA2017-badge/micropython-esp32,vitiral/micropython,mhoffma/micropython,jimkmc/micropython,adamkh/micropython,stonegithubs/micropython,dxxb/micropython,pfalcon/micropython,drrk/micropython,xuxiaoxin/micropython,PappaPeppar/micropython,emfcamp/micropython,adafruit/circuitpython,alex-march/micropython,cloudformdesign/micropython,deshipu/micropython,lowRISC/micropython,oopy/micropython,MrSurly/micropython-esp32,puuu/micropython,vitiral/micropython,hosaka/micropython,slzatz/micropython,matthewelse/micropython,ryannathans/micropython,Timmenem/micropython,suda/micropython,xuxiaoxin/micropython,cwyark/micropython,infinnovation/micropython,ahotam/micropython,jlillest/micropython,kostyll/micropython,micropython/micropython-esp32,misterdanb/micropython,omtinez/micropython,jimkmc/micropython,danicampora/micropython,xyb/micropython,slzatz/micropython,selste/micropython,cnoviello/micropython,adafruit/micropython,Timmenem/micropython,HenrikSolver/micropython,heisewangluo/micropython,galenhz/micropython,lowRISC/micropython,adafruit/micropython,vriera/micropython,xyb/micropython,cnoviello/micropython,noahchense/micropython,supergis/micropython,Timmenem/micropython,adamkh/micropython,jimkmc/micropython,tobbad/micropython,blazewicz/micropython,ceramos/micropython,hosaka/micropython,noahwilliamsson/micropython,tdautc19841202/micropython,xuxiaoxin/micropython,jmarcelino/pycom-micropython,adafruit/circuitpython,MrSurly/micropython-esp32,rubencabrera/micropython,neilh10/micropython,mpalomer/micropython,matthewelse/micropython,firstval/micropython,ernesto-g/micropython,lbattraw/micropython,galenhz/micropython,noahchense/micropython,ChuckM/micropython,bvernoux/micropython,henriknelson/micropython,redbear/micropython,bvernoux/micropython,ChuckM/micropython,AriZuu/micropython,cnoviello/micropython,matthewelse/micropython