I know that the title of this question is a duplicate of this Question and this Question but the solutions over there don't work for me and the error message is (slightly) different:
Error in grid.Call(L_textBounds, as.graphicsAnnot(x$label), x$x, x$y,  : 
polygon edge not found
(note the missing part about the missing font)
I tried all suggestions that I found (updating / reinstalling all loaded graphic packages, ggplot2, GGally, and scales, reinitialising the Fonts on Mac OSX by starting in safe mode, moving the Fonts from /Fonts/ (Disabled) back into /Fonts...) but none of it resolved the problem.
The error seems to occure when I plot a ggplot graph with
scale_y_continuous(label=scientific_10)
where scientific_10 is defined as 
scientific_10 <- function(x) {
parse(text = gsub("e", " %*% 10^", scientific_format()(x)))
}
Therefore the I suspect that the scales library has something to do with it. 
The most puzzling is that the error only occurs each so-and-so many times, maybe each 3rd or 5th time i try to plot the same graph...
> sessionInfo()
R version 3.2.2 (2015-08-14)
Platform: x86_64-apple-darwin13.4.0 (64-bit)
Running under: OS X 10.9.5 (Mavericks)
locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     
other attached packages:
[1] gridExtra_2.0.0 scales_0.3.0    broom_0.4.0     tidyr_0.3.1             ggplot2_1.0.1   GGally_0.5.0    dplyr_0.4.3    
loaded via a namespace (and not attached):
 [1] Rcpp_0.11.5      magrittr_1.5     MASS_7.3-43      mnormt_1.5-1         munsell_0.4.2    colorspace_1.2-6 lattice_0.20-33  R6_2.0.1        
 [9] stringr_0.6.2    plyr_1.8.1       tools_3.2.2      parallel_3.2.2       grid_3.2.2       gtable_0.1.2     nlme_3.1-121     psych_1.5.8     
[17] DBI_0.3.1        htmltools_0.2.6  lazyeval_0.1.10  yaml_2.1.13      assertthat_0.1   digest_0.6.8     reshape2_1.4.1   rmarkdown_0.8.1 
[25] labeling_0.3     reshape_0.8.5    proto_0.3-10    
traceback()
35: grid.Call(L_textBounds, as.graphicsAnnot(x$label), x$x, x$y, 
    resolveHJust(x$just, x$hjust), resolveVJust(x$just, x$vjust), 
    x$rot, 0)
34: widthDetails.text(x)
33: widthDetails(x)
32: (function (x) 
{
    widthDetails(x)
})(list(label = expression(5 %*% 10^+5, 7.5 %*% 10^+5, 1 %*% 
    10^+6, 1.25 %*% 10^+6, 1.5 %*% 10^+6), x = 1, y =   c(0.0777214770341215, 
0.291044141334423, 0.504366805634725, 0.717689469935027, 0.931012134235329
), just = "centre", hjust = 1, vjust = 0.5, rot = 0, check.overlap = FALSE, 
    name = "axis.text.y.text.8056", gp = list(fontsize = 9.6, 
        col = "black", fontfamily = "", lineheight = 0.9, font = 1L), 
    vp = NULL))
31: grid.Call.graphics(L_setviewport, vp, TRUE)
30: push.vp.viewport(X[[i]], ...)