Swap checks to get favor corruption before user error

[diondokter]

Fixes #70

[github-actions]

PR build size

  text	   data	    bss	    dec	    hex	filename
 16732	     56	  33808	  50596	   c5a4	example

Diff

    FILE SIZE        VM SIZE    
 --------------  -------------- 
  +0.0%     +33  [ = ]       0    .debug_info
  +0.4%     +32  [ = ]       0    .symtab
  +0.1%     +24  [ = ]       0    .strtab
  +0.0%     +16  [ = ]       0    .debug_frame
  +0.0%      +8  [ = ]       0    .debug_aranges
  -3.2%      -2  [ = ]       0    [Unmapped]
  -0.4%     -16  [ = ]       0    .debug_abbrev
  -0.0%     -18  [ = ]       0    .debug_line
  -0.0%     -29  [ = ]       0    .debug_loc
  -0.1%     -88  [ = ]       0    .debug_ranges
  -0.0%     -40  [ = ]       0    TOTAL