This patch should address the crashes when parsing a the crash report
frame dictionary.
If the crash report is not symbolicated, the `symbolLocation` key will
be missing. In that case, we should just use the `imageOffset`.
rdar://109836386
Differential Revision: https://reviews.llvm.org/D151844
Signed-off-by: Med Ismail Bennani <ismail@bennani.ma>