update docs for release 0.8.0 (#1419)

### What problem does this PR solve?

update docs for release 0.8.0

### Type of change

- [x] Documentation Update

---------

Co-authored-by: writinwaters <93570324+writinwaters@users.noreply.github.com>

graph/canvas.py

@@ -204,7 +204,8 @@ class Canvas(ABC):
             cpn = self.get_component(cpn_id)
             if not cpn["downstream"]: break
 
-            if self._find_loop(): raise OverflowError("Too much loops!")
+            loop = self._find_loop()
+            if loop: raise OverflowError(f"Too much loops: {loop}")
 
             if cpn["obj"].component_name.lower() in ["switch", "categorize", "relevant"]:
                 switch_out = cpn["obj"].output()[1].iloc[0, 0]
@@ -277,15 +278,18 @@ class Canvas(ABC):
 
         if len(path) < 2: return False
 
-        for l in range(1, len(path) // 2):
+        for l in range(2, len(path) // 2):
             pat = ",".join(path[0:l])
             path_str = ",".join(path)
             if len(pat) >= len(path_str): return False
-            path_str = path_str[len(pat):]
             loop = max_loops
-            while path_str.find(pat) >= 0 and loop >= 0:
+            while path_str.find(pat) == 0 and loop >= 0:
                 loop -= 1
-                path_str = path_str[len(pat):]
-            if loop < 0: return True
+                if len(pat)+1 >= len(path_str):
+                    return False
+                path_str = path_str[len(pat)+1:]
+            if loop < 0:
+                pat = " => ".join([p.split(":")[0] for p in path[0:l]])
+                return pat + " => " + pat
 
         return False

graph/component/categorize.py

@@ -38,7 +38,7 @@ class CategorizeParam(GenerateParam):
         self.check_empty(self.category_description, "[Categorize] Category examples")
         for k, v in self.category_description.items():
             if not k: raise ValueError(f"[Categorize] Category name can not be empty!")
-            if not v["to"]: raise ValueError(f"[Categorize] 'To' of category {k} can not be empty!")
+            if not v.get("to"): raise ValueError(f"[Categorize] 'To' of category {k} can not be empty!")
 
     def get_prompt(self):
         cate_lines = []

graph/component/generate.py

@@ -72,7 +72,10 @@ class Generate(ComponentBase):
         for para in self._param.parameters:
             cpn = self._canvas.get_component(para["component_id"])["obj"]
             _, out = cpn.output(allow_partial=False)
-            kwargs[para["key"]] = "\n - ".join(out["content"])
+            if "content" not in out.columns:
+                kwargs[para["key"]] = "Nothing"
+            else:
+                kwargs[para["key"]] = "\n - ".join(out["content"])
 
         kwargs["input"] = input
         for n, v in kwargs.items():