There is an Assertion `int decode_preR13_entities(BITCODE_RL, BITCODE_RL, unsigned int, BITCODE_RL, BITCODE_RL, Bit_Chain *, Dwg_Data *' failed at dwg2dxf: decode.c:5801 in libredwg v0.12.4.4608.
### system info
Ubuntu x86_64, clang 6.0, dwg2dxf([0.12.4.4608](https://github.com/LibreDWG/libredwg/releases/tag/0.12.4.4608))

### Command line
./programs/dwg2dxf -b -m @@ -o /dev/null

###  output
dwg2dxf: decode.c:5801: int decode_preR13_entities(BITCODE_RL, BITCODE_RL, unsigned int, BITCODE_RL, BITCODE_RL, Bit_Chain *, Dwg_Data *): Assertion `!dat->bit' failed.
Aborted

### poc
https://gitee.com/cxlzff/fuzz-poc/raw/master/libredwg/decode_preR13_entities_Assertion


Assertion dwg2dxf: decode.c:5801: int decode_preR13_entities(BITCODE_RL, BITCODE_RL, unsigned int, BITCODE_RL, BITCODE_RL, Bit_Chain *, Dwg_Data *): Assertion `!dat->bit' failed. Aborted. 
This is a GitHub Issue
repo:libredwg
owner:LibreDWG
Title : Assertion dwg2dxf: decode.c:5801: int decode_preR13_entities(BITCODE_RL, BITCODE_RL, unsigned int, BITCODE_RL, BITCODE_RL, Bit_Chain *, Dwg_Data *): Assertion `!dat->bit' failed. Aborted. 
Issue date:

--- start body ---
### system info
Ubuntu x86_64, clang 6.0, dwg2dxf([0.12.4.4608](https://github.com/LibreDWG/libredwg/releases/tag/0.12.4.4608))

### Command line
./programs/dwg2dxf -b -m @@ -o /dev/null

###  output
dwg2dxf: decode.c:5801: int decode_preR13_entities(BITCODE_RL, BITCODE_RL, unsigned int, BITCODE_RL, BITCODE_RL, Bit_Chain *, Dwg_Data *): Assertion `!dat->bit' failed.
Aborted

### poc
https://gitee.com/cxlzff/fuzz-poc/raw/master/libredwg/decode_preR13_entities_Assertion


--- end body ---

An assertion failure in the decode_preR13_entities function of the dwg2dxf tool in LibreDWG v0.12.4.4608 indicates a potential vulnerability that could be exploited to cause a denial of service (DoS) by providing specially crafted input files. The assertion failure suggests that the function is not handling certain input conditions correctly, which could lead to unexpected behavior or crashes.