Clean up a false error message in the LDM debug log

lib/compress/zstd_compress.c

@@ -4609,19 +4609,15 @@ size_t ZSTD_writeLastEmptyBlock(void* dst, size_t dstCapacity)
     }
 }
 
-size_t ZSTD_referenceExternalSequences(ZSTD_CCtx* cctx, rawSeq* seq, size_t nbSeq)
+void ZSTD_referenceExternalSequences(ZSTD_CCtx* cctx, rawSeq* seq, size_t nbSeq)
 {
-    RETURN_ERROR_IF(cctx->stage != ZSTDcs_init, stage_wrong,
-                    "wrong cctx stage");
-    RETURN_ERROR_IF(cctx->appliedParams.ldmParams.enableLdm == ZSTD_ps_enable,
-                    parameter_unsupported,
-                    "incompatible with ldm");
+    assert(cctx->stage == ZSTDcs_init);
+    assert(nbSeq == 0 || cctx->appliedParams.ldmParams.enableLdm != ZSTD_ps_enable);
     cctx->externSeqStore.seq = seq;
     cctx->externSeqStore.size = nbSeq;
     cctx->externSeqStore.capacity = nbSeq;
     cctx->externSeqStore.pos = 0;
     cctx->externSeqStore.posInSequence = 0;
-    return 0;
 }
 
 

lib/compress/zstd_compress_internal.h

@@ -1467,11 +1467,10 @@ size_t ZSTD_writeLastEmptyBlock(void* dst, size_t dstCapacity);
  * This cannot be used when long range matching is enabled.
  * Zstd will use these sequences, and pass the literals to a secondary block
  * compressor.
- * @return : An error code on failure.
  * NOTE: seqs are not verified! Invalid sequences can cause out-of-bounds memory
  * access and data corruption.
  */
-size_t ZSTD_referenceExternalSequences(ZSTD_CCtx* cctx, rawSeq* seq, size_t nbSeq);
+void ZSTD_referenceExternalSequences(ZSTD_CCtx* cctx, rawSeq* seq, size_t nbSeq);
 
 /** ZSTD_cycleLog() :
  *  condition for correct operation : hashLog > 1 */

lib/compress/zstdmt_compress.c

@@ -601,11 +601,8 @@ static void ZSTDMT_serialState_update(serialState_t* serialState,
     ZSTD_pthread_mutex_unlock(&serialState->mutex);
 
     if (seqStore.size > 0) {
-        size_t const err = ZSTD_referenceExternalSequences(
-            jobCCtx, seqStore.seq, seqStore.size);
+        ZSTD_referenceExternalSequences(jobCCtx, seqStore.seq, seqStore.size);
         assert(serialState->params.ldmParams.enableLdm == ZSTD_ps_enable);
-        assert(!ZSTD_isError(err));
-        (void)err;
     }
 }