`TypeError` in `slitherin`'s `nft_approve_warning` detector: 'LibraryCall' object is not subscriptable, even when excluded

[shargon]

I encountered a TypeError while running slither with slitherin detectors on my Solidity project. The crash seems to originate from the slitherin detector nft_approve_warning (pess-nft-approve-warning), specifically when processing library calls.

Notably, I was attempting to exclude this specific detector using the --exclude pess-nft-approve-warning flag in my Slither command. Despite this, the tool still crashed within this detector's logic.

Command Context:
The Slither command was structured similarly to:
slither --fail-none <path_to_contracts> --disable-color --json <output_json_path> --json-types console,detectors,list-detectors --exclude ...,pess-nft-approve-warning,...

Error and Traceback:
The analysis failed with the following traceback pointing to slitherin:

Traceback (most recent call last):
  File "/usr/local/bin/slitherin", line 8, in <module>
    sys.exit(main())
  File "/usr/local/lib/python3.10/dist-packages/slitherin/cli.py", line 189, in main
    handle_parser(parsed, unknown)
  File "/usr/local/lib/python3.10/dist-packages/slitherin/cli.py", line 115, in handle_parser
    run(
  File "/usr/local/lib/python3.10/dist-packages/slitherin/cli.py", line 82, in run
    for r in [output.data for output in self._detect()]:
  File "/usr/local/lib/python3.10/dist-packages/slitherin/detectors/nft_approve_warning.py", line 67, in _detect
    for d in self._detect_arbitrary_from(f):
  File "/usr/local/lib/python3.10/dist-packages/slitherin/detectors/nft_approve_warning.py", line 35, in _detect_arbitrary_from
    all_library_calls = [f_called[1].solidity_signature for f_called in f.library_calls]
  File "/usr/local/lib/python3.10/dist-packages/slitherin/detectors/nft_approve_warning.py", line 35, in <listcomp>
    all_library_calls = [f_called[1].solidity_signature for f_called in f.library_calls]
TypeError: 'LibraryCall' object is not subscriptable

The process then indicated: Exception: Errored out with code: 1, while running slither

Expected Behavior:

1. The excluded detector (pess-nft-approve-warning) should not run or cause a crash.
2. If the detector must be loaded for some reason despite exclusion, it should not raise a TypeError.
3. The analysis should complete without the tool itself crashing.

Actual Behavior:
slitherin crashed due to a TypeError in the nft_approve_warning.py detector when trying to access f_called[1], where f_called is a LibraryCall object. This occurred even though the detector was specified in the --exclude list.

More data:

Executed with --separated

INFO:slitherinLogger:'slither --fail-none /xxx/evm --disable-color --json /slithering-result-2.json --json-types console,detectors,list-detectors --exclude pess-arb-prevrandao-difficulty,pess-arb-block-number-timestamp,pess-arb-chainlink-price-feed,pess-double-entry-token-alert,pess-unprotected-setter,pess-nft-approve-warning,pess-inconsistent-nonreentrant,pess-strange-setter,pess-only-eoa-check,pess-magic-number,pess-dubious-typecast,pess-multiple-storage-read,pess-timelock-controller,pess-tx-gasprice,pess-unprotected-initialize,pess-event-setter,pess-before-token-transfer,pess-uni-v2,pess-token-fallback,pess-for-continue-increment,pess-arbitrary-call,pess-ecrecover,pess-public-vs-external,pess-aave-flashloan-callback,pess-potential-arithmetic-overflow,pess-curve-readonly-reentrancy,pess-balancer-readonly-reentrancy,pess-vyper-version-reentrancy,pess-price-manipulation' running (wd: /)

Last output

Only slitherin results:
00:10.841 error --ignore-compile used, if something goes wrong, consider removing the ignore compile flag
00:10.841 error Magic number 32 is used multiple times in:
00:10.841 error 	_addressBytes.length > 32 (node_modules/@layerzerolabs/lz-evm-protocol-v2/contracts/libs/AddressCast.sol#10)
00:10.841 error 	offset = 32 - _addressBytes.length (node_modules/@layerzerolabs/lz-evm-protocol-v2/contracts/libs/AddressCast.sol#13)
00:10.841 error 	mstore(uint256,uint256)(result + 32,_addressBytes32 << offset) (node_modules/@layerzerolabs/lz-evm-protocol-v2/contracts/libs/AddressCast.sol#28)
00:10.841 error Reference: https://github.com/pessimistic-io/slitherin/blob/master/docs/magic_number.md
00:10.841 error Traceback (most recent call last):
00:10.841 error   File "/usr/local/bin/slither", line 8, in <module>
00:10.841 error     sys.exit(main())
00:10.841 error   File "/usr/local/lib/python3.10/dist-packages/slither/__main__.py", line 776, in main
00:10.841 error     main_impl(all_detector_classes=detectors, all_printer_classes=printers)
00:10.841 error   File "/usr/local/lib/python3.10/dist-packages/slither/__main__.py", line 882, in main_impl
00:10.841 error     ) = process_all(filename, args, detector_classes, printer_classes)
00:10.841 error   File "/usr/local/lib/python3.10/dist-packages/slither/__main__.py", line 107, in process_all
00:10.841 error     ) = process_single(compilation, args, detector_classes, printer_classes)
00:10.841 error   File "/usr/local/lib/python3.10/dist-packages/slither/__main__.py", line 87, in process_single
00:10.841 error     return _process(slither, detector_classes, printer_classes)
00:10.841 error   File "/usr/local/lib/python3.10/dist-packages/slither/__main__.py", line 137, in _process
00:10.841 error     detector_resultss = slither.run_detectors()
00:10.841 error   File "/usr/local/lib/python3.10/dist-packages/slither/slither.py", line 292, in run_detectors
00:10.841 error     results = [d.detect() for d in self._detectors]
00:10.841 error   File "/usr/local/lib/python3.10/dist-packages/slither/slither.py", line 292, in <listcomp>
00:10.841 error     results = [d.detect() for d in self._detectors]
00:10.841 error   File "/usr/local/lib/python3.10/dist-packages/slither/detectors/abstract_detector.py", line 203, in detect
00:10.841 error Traceback (most recent call last):
00:10.841 error   File "/usr/local/bin/slitherin", line 8, in <module>
00:10.841 error     sys.exit(main())
00:10.841 error   File "/usr/local/lib/python3.10/dist-packages/slitherin/cli.py", line 189, in main
00:10.841 error     handle_parser(parsed, unknown)
00:10.841 error   File "/usr/local/lib/python3.10/dist-packages/slitherin/cli.py", line 115, in handle_parser
00:10.841 error     run(
00:10.841 error   File "/usr/local/lib/python3.10/dist-packages/slitherin/cli.py", line 82, in run
00:10.841 error     for r in [output.data for output in self._detect()]:
00:10.841 error   File "/usr/local/lib/python3.10/dist-packages/slitherin/detectors/nft_approve_warning.py", line 67, in _detect
00:10.841 error     for d in self._detect_arbitrary_from(f):
00:10.841 error   File "/usr/local/lib/python3.10/dist-packages/slitherin/detectors/nft_approve_warning.py", line 35, in _detect_arbitrary_from
00:10.841 error     all_library_calls = [f_called[1].solidity_signature for f_called in f.library_calls]
00:10.841 error   File "/usr/local/lib/python3.10/dist-packages/slitherin/detectors/nft_approve_warning.py", line 35, in <listcomp>
00:10.841 error     all_library_calls = [f_called[1].solidity_signature for f_called in f.library_calls]
00:10.841 error TypeError: 'LibraryCall' object is not subscriptable
00:10.841 error Failed to run slither: Errored out with code: 1, while running slither
00:10.841 error     raise e
00:10.841 error   File "/usr/local/lib/python3.10/dist-packages/slitherin/cli.py", line 76, in run
00:10.841 error     raise Exception(
00:10.841 error Exception: Errored out with code: 1, while running slither