[R-SIG-Mac] png error message problem, and potential crash

[Richard M. Heiberger]

bash-3.2$ R --vanilla

R version 3.4.0 Patched (2017-04-28 r72639) -- "You Stupid Darkness"
Copyright (C) 2017 The R Foundation for Statistical Computing
Platform: x86_64-apple-darwin15.6.0 (64-bit)

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> png("abcd.png", height=.22, width=2)
Jun 22 12:13:08  R[59491] <Error>: CGContextTranslateCTM: invalid
context 0x0. If you want to see the backtrace, please set
CG_CONTEXT_SHOW_BACKTRACE environmental variable.
Jun 22 12:13:08  R[59491] <Error>: CGContextScaleCTM: invalid context
0x0. If you want to see the backtrace, please set
CG_CONTEXT_SHOW_BACKTRACE environmental variable.
> png("abcd.png", height=.22, width=2, units="in", res=300)
> dev.cur()
quartz_off_screen
                3
> dev.off()
quartz_off_screen
                2
> dev.off()
null device
          1
> version
               _
platform       x86_64-apple-darwin15.6.0
arch           x86_64
os             darwin15.6.0
system         x86_64, darwin15.6.0
status         Patched
major          3
minor          4.0
year           2017
month          04
day            28
svn rev        72639
language       R
version.string R version 3.4.0 Patched (2017-04-28 r72639)
nickname       You Stupid Darkness
> q()
bash-3.2$

Deep inside a function with png() inside a loop,
after about 70 of the CGContextTranslateCTM messages,
I got the crash message
Jun 22 11:40:48  R[59174] <Error>: CGBitmapContextCreateImage: invalid
context 0x0. If you want to see the backtrace, please set
CG_CONTEXT_SHOW_BACKTRACE environmental variable.

Process R trace/BPT trap: 5 at Thu Jun 22 11:40:48 2017


For comparison, on Windows
R version 3.4.0 Patched (2017-04-28 r72638) -- "You Stupid Darkness"
Copyright (C) 2017 The R Foundation for Statistical Computing
Platform: x86_64-w64-mingw32/x64 (64-bit)

I get an appropriate error message

> png("abcd.png", height=.22, width=2)
Warning message:
In png("abcd.png", height = 0.22, width = 2) :
  'width=2, height=0' are unlikely values in pixels
>

For completeness, the repair, shown above, is to use the units and res
arguments.