[TVMScript] Handle undefined functions when dumping IRModule

[ConvolutedDog]

PrimFuncPass temporarily clears the module slot for the function being transformed before calling pass_func. Dumping the IRModule mid-pass can therefore see undefined BaseFuncs and crash in SortableFunction when calling tvm::Dump(). Guard with func.defined(), assign a fallback sort priority, and log instead of dereferencing.

[gemini-code-assist]

Code Review

This pull request updates the SortableFunction constructor in src/script/printer/ir/ir.cc to handle undefined functions, assigning them a specific priority and logging an info message to prevent crashes during debugging. The reviewer identified that the current implementation inconsistently handles the main function when it is undefined and noted that a crash could still occur later in the printing loop. A refactoring was suggested to check for undefined functions first and ensure consistent logging and priority assignment.

[tlopex]

LGTM