Fix: empty chunk issue. (#12638)

#12570

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

rag/flow/splitter/splitter.py

@@ -93,6 +93,8 @@ class Splitter(ProcessBase):
                     split_sec = re.split(r"(%s)" % custom_pattern, c, flags=re.DOTALL)
                     if split_sec:
                         for j in range(0, len(split_sec), 2):
+                            if not split_sec[j].strip():
+                                continue
                             docs.append({
                                 "text": split_sec[j],
                                 "mom": c
@@ -156,6 +158,8 @@ class Splitter(ProcessBase):
                 if split_sec:
                     c["mom"] = c["text"]
                     for j in range(0, len(split_sec), 2):
+                        if not split_sec[j].strip():
+                            continue
                         cc = deepcopy(c)
                         cc["text"] = split_sec[j]
                         docs.append(cc)