[LLLDB] Adding additional check LibCppStdFunctionCallableInfo based on crash reports

We have seen several crashes in LibCppStdFunctionCallableInfo(...) but we don't have a
reproducer. The last crash pointed to last call to line_entry_helper(...) and symbol
was a nullptr. So adding a check for this case.

GitOrigin-RevId: ebee45713190d9844ef860bf491035e3dcf3a538
1 file changed