Failure to read LaTeX images when there is too much LaTeX

[Myridium]

If a message has too much LaTeX, sometimes some of the LaTeX will fail to render and an error will occur:

"Error while reading the generated image!

Failed to open file '/tmp/purpleXXXXXX.png': No such file or directory"

I'm unable to work out exactly what kind of message causes the error, but this specific example consistently reproduces the problem:

Suppose that $$ a , b > 0 $$. Then $$|a + b| = a + b = |a| + |b|$$.
Suppose that $$a,b < 0$$. Then $$|a + b| = -a - b = |a| + |b|$$.
Suppose, WLOG, that $$a = 0$$. Then $$|a + b| = |b| = |0| + |b| = |a| + |b|$$.
Suppose, WLOG, that $$a<0$$ and $$b>0$$.
1) Suppose that $$|a| > |b|$$. Then $$|a + b| = |a| - |b| \leq |a| + |b|$$.
2) Suppose that $$|a| < |b|$$. Then $$|a + b| = |b| - |a| \leq |a| + |b|$$.