fix text split (#15426)

api/core/rag/splitter/fixed_text_splitter.py

@@ -88,6 +88,9 @@ class FixedRecursiveCharacterTextSplitter(EnhanceRecursiveCharacterTextSplitter)
                 break
         # Now that we have the separator, split the text
         if separator:
+            if separator == " ":
+                splits = text.split()
+            else:
                 splits = text.split(separator)
         else:
             splits = list(text)