The following plantuml code leads to a crash, which is fixed by either using another dash in line 14 (g <-- a) or adding a whitespace at the end of the line:
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class a
class b
class c
class d
class e
class f
class g
a -> b
a --> c
a ---> d
e <- a
f <-- a
g <- a
f <-- g
'g --> f
---