Misc. bug: needless exception handling in `llm_chat_detect_template`

[AnonN10]

Name and Version

version: 6877 (10fcc41)
built with Clang 17.0.3 for x64

Operating systems

No response

Which llama.cpp modules do you know to be affected?

No response

Command line

Problem description & steps to reproduce

llm_chat_template_from_str throws, as it simply is a std::map lookup via std::map::at(), almost useless wrapper. Then in the llm_chat_detect_template function it is wrapped in a try-catch block, which ignores the exception std::out_of_range, yet still pollutes the output with "exception thrown" message, and incurs negligible overhead. My main issue is the output pollution, so I propose to refactor the function to use sentinel value LLM_CHAT_TEMPLATE_UNKNOWN that already exists, and to check for that instead of catching exceptions.

First Bad Commit

No response

Relevant log output

Exception thrown at 0x00007FFF2A7FCD29 in chat.exe: Microsoft C++ exception: std::out_of_range at memory location 0x00000005BF5CF780.

[AnonN10]

This behavior can be seen in the simple-chat example.